This PDF file contains the front matter associated with SPIE Proceedings Volume 9748, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and Conference Committee listing.

This paper firstly introduces c-BN in general and its excellent properties that make c-BN a promising candidate competing with diamond as hard coating and as a future high temperature semiconductor material. Furthermore, this paper gives an overview of the recent advances of the different synthetic techniques towards the heteroepitaxial growth of c-BN films. In the end, it will describe the state of the art of n-type doping of these c-BN epitaxial films through which a c-BN/diamond pn diode can be anticipated.

Advanced Substrates consist of a 200-nm-thick GaN layer bonded to a handler wafer. The thin layer is separated from source material by Smart Cut^TM technology. GaN on Sapphire Advanced Substrates were used as seeds in HVPE-GaN growth. Unintentionally doped and silicon-doped GaN layers were crystallized. Free-standing HVPE-GaN was characterized by X-ray diffraction, defect selective etching, photo-etching, Hall method, Raman spectroscopy, and secondary ion mass spectrometry. The results were compared to HVPE-GaN grown on standard MOCVD-GaN/sapphire templates.

We report on green-emitting In0.18Ga0.82N/GaN multi-quantum well (MQW) structures over a variety of metalorganic chemical vapor deposition (MOCVD) growth conditions to examine the morphology, optical quality, and micron-scale emission properties. The MOCVD growth parameter space was analyzed utilizing two orthogonal metrics which allows comparing and optimizing growth conditions over a wide range of process parameters: effective gas speed, S*, and effective V/III ratio, V/III*. Optimized growth conditions with high V/III, low gas speed, and slow growth rates resulted in improved crystal quality, PL emission efficiency, and micron-scale wavelength uniformity. One of the main challenges in green MQWs with high Indium content is the formation of Indium inclusion type defects due to the large lattice mismatch combined with the miscibility gap between GaN and InN. An effective way of eliminating Indium inclusions was demonstrated by introducing a small fraction of H₂ (2.7%) in the gas composition during the growth of high temperature GaN quantum barriers. In addition, the positive effects of employing an InGaN/GaN superlattice (SL) underlayer to crystal quality and micron-scale emission uniformity was demonstrated, which is of special interest for applications such as micro-LEDs.

Compositional grading of InGaN/GaN multi quantum wells (QWs) was proposed to mitigate polarization effects and Auger losses in InGaN-based light emitting diodes [K. P. O'Donnell et al., Phys. Status Solidi RRL 6 (2012) 49]. In this paper we are reviewing our recent attempts on achieving such gradient via quantum well intermixing. Annealing up to 1250 °C resulted in negligible interdiffusion of QWs and barriers revealing a surprising thermal stability well above the typical MOCVD growth temperatures. For annealing at 1400 °C results suggest a decomposition of the QWs in regions with high and low InN content. The defect formation upon nitrogen implantation was studied in detail. Despite strong dynamic annealing effects, which keep structural damage low, the created defects strongly quench the QW luminescence even for low implantation fluences. This degradation could not be reversed during thermal annealing and is hampering the use of implantation induced quantum well intermixing in InGaN/GaN structures.

We have developed a novel conductivity based selective electrochemical etching to introduce nanometer sized pores into GaN. By controlling the doping and electrochemical etching bias, we are able to control the pore morphology. The nanoporous (NP) GaN can be considered a new form of GaN with an unprecedented tunability in optical index We show the potential of this NPGaN to overcome the optical and epitaxial limitations of AlGaN, which has been the bottleneck for GaN-based laser diodes for decades. The advantages of NP-GaN for both vertical surfaceemitting laser diodes (VCSEL) and edge-emitting laser diodes are exhibited in subsequent sections. We first demonstrate the record high reflectances (R > 99.5 %) from epitaxial NP-GaN mirrors, which are used in a low threshold optically pumped VCSEL. We then show a two-fold increase of modal gain in an edge-emitting waveguide geometry with optical confinement Γ engineering. The increase of the Γ also leads to a two-fold reduction in the threshold power density under optical pumping with a threshold material gain of 400 cm^-1, which is more than two times lower than previously reported (> 1,000 cm^-1).

Radiative and non-radiative recombination lifetimes in III-nitride semiconductors are usually estimated from time-resolved and temperature-dependent photoluminescence (PL) measurements by assuming that internal quantum efficiency (IQE) at cryogenic temperature is unity. In our recent study, we found that the assumption is not necessarily valid, from simultaneous measurements of PL and photo-acoustic (PA) signals. In this study, we estimate accurate lifetimes from the reliable IQE values estimated by the simultaneous PL/PA measurements, and it is found that radiative lifetime in GaN increases in proportion to the 1.5th power of temperature and that non-radiative lifetime shows little temperature dependence although the non-radiative lifetime itself largely depends on sample quality.

Various semipolar AlGaN/AlN quantum wells (QWs) with atomically smooth surfaces and abrupt interfaces are fabricated on AlN bulk substrates. While keeping the crystal qualities, we can easily adjust the Al compositions in the semipolar AlGaN QWs by changing growth temperatures, similar to the case of conventional (0001) AlGaN QWs. Due to the small internal electric fields in the semipolar QWs, the energy fluctuations are extremely suppressed and the radiative recombination lifetimes are drastically shortened, compared with the (0001) QWs. The shorter radiative recombination lifetimes realize much stronger emissions from the semipolar QWs.

The results of the influence of point defects (vacancy with interstitial atom) on the GaN/AlN heterointerface is presented. It was ascertained that presence of Al atom vacancy in the heterointerface leads to the contacting layer atoms rearrangement. The presence of N atom vacancy does not influence on the contacting Ga and Al layers intermixing.

The selective and low-damaged etching of p-type GaN or AlGaN layer is inevitable process for AlGaN/GaN high-power transistors. We have investigated an electrochemical etching of p-GaN layer grown on AlGaN/GaN heterostructures, consisting of an anodic oxidation of p-GaN surface and a subsequent dissolution of the resulting oxide. The p-GaN layer was electrochemically etched by following the pattern of the SiO₂ film that acted as an etching mask. Etching depth was linearly controlled by cycle number of triangular waveform at a rate of 25 nm/cycle. The AFM, TEM and μ-AES results showed that the top p-GaN layer was completely removed after 5 cycles applied, and the etching reaction was automatically sopped on the AlGaN surface. I-V and C-V measurements revealed that no significant damages were induced in the AlGaN/GaN heterostructures.

GaN-based metal-oxide-semiconductor high-electron-mobility transistors (MOSHEMTs) with outstanding properties of high operation speed and high breakdown voltage are promising for high frequency switching operation in ICs. To further develop the GaN-based digital ICs, the AlGaN/GaN MOSHEMT inverters integrated with the enhancement/depletion-mode (E/D-mode) transistors were investigated. In this work, the ferroelectric LiNbO₃ (LNO) gate oxide layer and the photoelectrochemical (PEC)-recessed structure were simultaneously utilized to fabricate the critical E-mode AlGaN/GaN MOSHEMTs. Among the ferroelectric materials, the high dielectric constant LNO film with the larger spontaneous polarization of 80 μC/cm², the wider bandgap of 3.9 eV, and the lower interface state density on the GaN-based semiconductor was beneficial to the modulation of the two-dimensional electron gas (2DEG) channel and the reduction of the gate leakage current. Besides, using the PEC-recessed structure could improve the transconductance of the E-mode transistors and adjust the operation current of the D-mode transistors without destroying the etched AlGaN surface. Instead of the typical tuning area size method, the PEC etching method was demonstrated in this work to adjust the current ratio (β) of the E/D-mode transistors with keeping the matched area size for the miniaturization of the AlGaN/GaN MOSHEMT inverters. From the voltage transfer curve, the corresponded V_OUT was equaled to V_IN = V_DD/2 = 2.5 V, and the output swing were about 4.9 V_p-p as the input signal was 5 V_p-p. It revealed that the resulting AlGaN/GaN MOSHEMT inverter with the β of 25 was operated as a high performance un-skewed inverter.

We report our current development progress of ultraviolet vertical-cavity surface-emitting lasers, which included the development of an electrically conducting n-DBR consisting of 40-pairs of Si-doped quarter-wavelength layers of Al_0.12Ga_0.88N and GaN. A peak reflectivity of 91.6% at 368 nm was measured and a series resistance of 17.7Ω was extracted near the maximum measured current of 100 mA. Furthermore, a micro-cavity light emitting diode was demonstrated by utilizing the established n-DBR. A 2λ cavity was subsequently grown on the 40-pair Al_0.12Ga_0.88N/GaN n-DBR and a peak wavelength of 371.4 nm was observed with spectral linewidth of 5.8 nm.

We have succeeded in achieving continuous-wave operation of gallium nitride (GaN) based vertical-cavity surfaceemitting lasers (VCSELs), which was fabricated by epitaxial lateral overgrowth (ELO) using dielectric distributed Bragg reflectors(DBRs) as masks for selective growth. The device exhibited CW operation at a wavelength of 453.9nm. The maximum output power was 1.1 mW, which is the highest value reported in previously published articles. The ELO process used for this study represents a breakthrough for challenges which were indicated by other former reports for GaN-based VCSELs and is suitable for mass production.

We propose optical-loss suppressed thick-optical-waveguide (TOW) InGaN laser diodes (LDs) without operatingvoltage increase. A record high continuous-wave (CW) output of 7.2W for a single-emitting InGaN LD is achieved without thermal peak-out in the light-current curve. The TOW enables to confine major part of the propagating light into a transparent undoped region, and thus significantly reduces the optical-loss. An electron-overflow-suppression (EOS) layer placed between the waveguide layer and a p-cladding layer plays an important role to reduce the operating voltage after introduction of the undoped TOW layer. We executed a self-consisted calculation of voltage-current characteristics taking into account Schrödinger and Poisson equations in conjunction with a carrier continuity equation. The calculation result indicates possible presence of conductivity-modulation in the waveguide filled with electrons reflected backward by the EOS layer and holes injected from the p-type cladding layer. We successfully demonstrated the optical-loss suppressed operation resulting in the slope efficiency (SE) increase from 2.0W/A to 2.5W/A. It is noted that the operating voltage of the TOW LD is nearly identical to the conventional LD thanks to the above conductivitymodulation phenomenon. The presented result suggests that our TOW structure can overcome the optical-loss drawback of the InGaN LDs, and hence will lead them to the applications requiring high wattage light sources.

Gallium Nitride (GaN) laser diodes fabricated from the AlGaInN material system is an emerging technology that allows laser diodes to be fabricated over a very wide wavelength range from u.v. to the visible, and is a key enabler for the development of new system applications such as (underwater and terrestrial) telecommunications, quantum technologies, display sources and medical instrumentation.

We report on deeply etched sidewall grating DFB lasers in the InGaN/GaN material system emitting at a single wavelength around 434 nm. GaN lasers have a wide range of applications in communications, displays and storage. The availability of a single wavelength device with a good side mode suppression ratio (SMSR) would allow further applications to be addressed such as sources for laser cooling and Fraunhofer line operation for solar background free communications. Sidewall etched gratings have the advantage of fabrication with no need for overgrowth and have been demonstrated in a range of other material systems and wavelengths. Importantly for GaN based devices, this design has the potential to minimise fabrication induced damage to the epi structure. We investigated two laser designs, one with 80 % duty-cycle 3rd order gratings and another with 39th order partial gratings. Simulation of the 2D waveguide sections was carried out to find the optimal grating width. For fabrication, the laser ridge and gratings were patterned in a single step using electron beam lithography and ICP etched to a depth of 500 nm. Contact metal was deposited and the sample thinned and cleaved into 1 mm long cavities. The as-cleaved 3rd order lasers emit in the pulsed regime with a SMSR of 20 dB and a peak single-mode output power of 40 mW. The output power is similar to that of parallel processed FP lasers. The 39th order lasers also exhibit narrow spectral width at an output power of 10 mW.

We report on the lasing of III-nitride nonpolar, violet, vertical-cavity surface-emitting lasers (VCSELs) with IIInitride tunnel-junction (TJ) intracavity contacts and ion implanted apertures (IIAs). The TJ VCSELs are compared to similar VCSELs with tin-doped indium oxide (ITO) intracavity contacts. Prior to analyzing device results, we consider the relative advantages of III-nitride TJs for blue and green emitting VCSELs. The TJs are shown to be most advantageous for violet and UV VCSELs, operating near or above the absorption edge for ITO, as they significantly reduce the total internal loss in the cavity. However, for longer wavelength III-nitride VCSELs, TJs primarily offer the advantage of improved cavity design flexibility, allowing one to make the p-side thicker using a thick n-type III-nitride TJ intracavity contact. This offers improved lateral current spreading and lower loss, compare to using ITO and p-GaN, respectively. These aspects are particularly important for achieving high-power CW VCSELs, making TJs the ideal intracavity contact for any III-nitride VCSEL. A brief overview of III-nitride TJ growth methods is also given, highlighting the molecular-beam epitaxy (MBE) technique used here. Following this overview, we compare 12 μm aperture diameter, violet emitting, TJ and ITO VCSEL experimental results, which demonstrate the significant improvement in differential efficiency and peak power resulting from the reduced loss in the TJ design. Specifically, the TJ VCSEL shows a peak power of ~550 μW with a threshold current density of ~3.5 kA/cm², while the ITO VCSELs show peak powers of ~80 μW and threshold current densities of ~7 kA/cm².

We report and discuss the origins of linearly polarized single photon emission from site-controlled GaN nanowire quantum dots. The observed single photon emission reveals almost complete linear polarization, in agreement with studies in the literature, which could be of use for applications such as quantum key distribution.

The maximum achievable reflectivity of current III-nitride Bragg reflectors in the UV-C spectral range is limited due to plastic relaxation of thick multilayer structures. Cracking due to a large mismatch of the thermal expansion and lattice constants between Al_xGa_1-xN/Al_yGa_1-yN alloys of different composition and the substrate at the heterointerface is the common failure mode. Strain engineering and strain relaxation concepts by the growth on a strain reduced Al_0.85Ga_0.15N template and the implementation of low temperature interlayers is demonstrated. A significant enhancement of the maximum reflectivity above 97% at a resonance wavelength of 270 nm due to an increase of the critical thickness of our AlN/Al_0.65Ga_0.35N DBRs to 1.45 μm (25.5 pairs) prove their potential. By comparing the growth of identical Bragg reflectors on different pseudo-templates, the accumulated mismatch strain energy in the DBR, not the dislocation density provided by the template/substrate, was identified to limit the critical thickness. To further enhance the reflectivity low temperature interlays were implemented into the DBR to partially relief the misfit strain. Relaxation is enabled by the nucleation of small surface domains facilitating misfit dislocation injection and glide. Detailed structural and optical investigations will be conducted to prove the influence of the LT-AlN interlayers on the strain state, structural integrity and reflectivity properties. Coherent growth and no structural and optical degradation of the Bragg mirror properties was observed proving the fully applicability of the relaxation concept to fabricate thick high reflectivity DBR and vertical cavity laser structures.

Nearly all the air-water purification/polymer curing systems and bio-medical instruments require 250-300 nm wavelength ultraviolet light for which mercury lamps are primarily used. As a potential replacement for these hazardous mercury lamps, several global research teams are developing AlGaN based Deep Ultraviolet (DUV) light emitting diodes (LEDs) and DUV LED Lamps and Laser Diodes over Sapphire and AlN substrates. In this paper, we review the current research focus and the latest device results. In addition to the current results we also discuss a new quasipseudomorphic device design approach. This approach which is much easier to integrate in a commercial production setting was successfully used to demonstrate UVC devices on Sapphire substrates with performance levels equal to or better than the conventional relaxed device designs.

In this paper we report on the influence of the heterostructure design of (InAlGa)N-based UV-B LEDs grown by metalorganic vapor phase epitaxy on sapphire substrates on the degradation behavior of the device. Two types of LEDs with different heterostructure design, resulting in peak-wavelengths of about 290 nm and 310 nm, respectively, were stressed at a constant operation current of 100 mA and a heat sink temperature of 20°C. Electro-optical characterization of the LEDs over 1.000 h of operation shows two different degradation modes with respect to the change of the emission spectrum and leakage current. The first mode during the initial hours (290 nm LED: 0 h - 500 h, 310 nm LED: 0 h – 100 h) of operation is represented by a fast reduction of the quantum well (QW) luminescence, a constant or increasing parasitic luminescence between 310 nm and 450 nm and a fast increase of the reverse- and forward-bias leakage current. These changes are more pronounced (higher degradation rate) in the 290 nm LEDs and can therefore be attributed to the different heterostructure design. In contrast, the second degradation mode at longer operation times (290 nm LED: >500 h, 310 nm LED: >100 h) is marked by a slow reduction of both the QW and the parasitic luminescence, as well as a slow increase of the leakage current which are similar for both types of LEDs. Furthermore, the second mode is marked by a square-root time dependence of the QW luminescence intensity, indicating a diffusion process to be involved.

The monolithic integration of red, green and blue (RGB) GaN-based light-emitting diodes (LEDs) directly on a single chip is critically important for smart lighting and full color display applications. In this work, RGB InGaN/GaN dot-in-a-wire LED arrays were laterally arranged on a Si wafer using a three-step SiO_x-mask selective area growth (SAG) technique, and on a sapphire wafer using a Ti-mask SAG technique. Tunable emission across the entire visible spectral range (~ 450 nm to 700 nm) can be readily achieved on a single Si wafer by varying the sizes and/or compositions of the dots. By separately biasing lateral-arranged multi-color LED subpixels, the correlated color temperature (CCT) values of such a ~ 0.016 mm² pixel can be varied from ~ 1900 K to 6800 K. The RGB pixel size can be further reduced by using the Ti-mask SAG technique on sapphire wafer. Full-color InGaN/GaN nanowire arrays with sizes of 2.8 × 2.8 μm² have been monolithically fabricated into the same pixel.

We demonstrate high-efficiency blue light-emitting diodes (LEDs) with thin AlGaN interlayers in InGaN/GaN multiquantum wells (MQWs) grown on Si (111) substrates. The peak external quantum efficiency (EQE) η_EQE of 82% at room temperature and the hot/cold factor (HCF) of 94% have been obtained by using the functional thin AlGaN interlayers in the MQWs in addition to reducing threading dislocation densities (TDDs) in the blue LEDs. An HCF is defined as η_EQE(85°C)/η_EQE(25°C). The blue LED structures were grown by metal-organic chemical vapor deposition on Si (111) substrates. The MQWs applied as an active layer have 8- pairs of InGaN/Al_yGa_1-yN/GaN (0≤y≤1) heterostructures. Thinfilm LEDs were fabricated by removing the Si (111) substrates from the grown layers. It is observed by high-resolution transmission electron microscopy and three-dimensional atom probe analysis that the 1 nm-thick Al_yGa_1-yN interlayers, whose Al content is y=0.3 or less, are continuously formed. EQE and the HCFs of the LEDs with thin Al_0.15Ga_0.85N interlayers are enhanced compared with those of the samples without the interlayers in the low-current-density region. We consider that the enhancement is due to both the reduction of the nonradiative recombination centers and the increase of the radiative recombination rate mediated by the strain-induced hole carriers indicated by the simulation of the energy band diagram.

We report on the reliability of GaN-based super-luminescent light emitting diodes (SLEDs) emitting at a wavelength of 405 nm. We show that the Mg doping level in the p-type layers has an impact on both the device electro-optical characteristics and their reliability. Optimized doping levels allow decreasing the operating voltage on single-mode devices from more than 6 V to less than 5 V for an injection current of 100 mA. Furthermore, maximum output powers as high as 350 mW (for an injection current of 500 mA) have been achieved in continuous-wave operation (CW) at room temperature. Modules with standard and optimized p-type layers were finally tested in terms of lifetime, at a constant output power of 10 mW, in CW operation and at a case temperature of 25 °C. The modules with non-optimized p-type doping showed a fast and remarkable increase in the drive current during the first hundreds of hours together with an increase of the device series resistance. No degradation of the electrical characteristics was observed over 2000 h on devices with optimized p-type layers. The estimated lifetime for those devices was longer than 5000 h.

Internal quantum efficiency (IQE) is usually estimated from temperature dependence of photoluminescence (PL) intensity by assuming that the IQE at cryogenic temperature is unity. III-nitride samples, however, usually have large defect-density, and the assumption is not necessarily valid. In this study, we developed a new method to estimate accurate IQE values by simultaneous PL and photo-acoustic (PA) measurements, and demonstratively evaluated the IQE values for various GaN samples. The results show that the conventional method cannot give accurate IQE values for low-quality samples although it can be valid for high-quality samples, and that our method can always give accurate values.

We report a semipolar III-nitride device in which an electrically injected blue light emitting diode optically pumps monolithic long wavelength emitting quantum wells (QWs) to create polarized white light. We have demonstrated an initial device with emission peaks at 440 nm and 560 nm from the electrically injected and optically pumped QWs, respectively. By tuning the ratio of blue to yellow, white light was measured with a polarization ratio of 0.40. High indium content InGaN is required for long wavelength emission but is difficult to achieve because it requires low growth temperatures and has a large lattice mismatch with GaN. This device design incorporates optically pumped QWs for long wavelength emission because they offer advantages over using electrically injected QWs. Optically pumped QWs do not have to be confined within a p-n junction, and carrier transport is not a concern. Thus, thick GaN barriers can be incorporated between multiple InGaN QWs to manage stress. Optically pumping long wavelength emitting QWs also eliminates high temperature steps that degrade high indium content InGaN but are required when growing p-GaN for an LED structure. Additionally, by eliminating electrical injection, the doping profile can instead be engineered to affect the emission wavelength. We discuss ongoing work focused on improving polarized white light emission by optimizing the optically pumped QWs. We consider the effects of growth conditions, including: trimethylindium (TMI) flow rate, InGaN growth rate, and growth temperature. We also examine the effects of epitaxial design, including: QW width, number of QWs, and doping.

Gallium nitride nanostructures have been receiving considerable attention as building blocks for nanophotonic technologies due to their unique high aspect ratios, promising the realization of photonic and biological nanodevices such as blue light emitting diodes (LEDs), short-wavelength ultraviolet nanolasers and nanofluidic biochemical sensors. In this study, we report on the hierarchical growth of GaN nanowires (NWs) by dynamically adjusting the growth parameters using pulsed flow metalorganic chemical vapor deposition (MOCVD) technique. We carried out two step growth processes to grow hierarchical GaN NWs. At the first step the GaN NWs were grown at 950°C and in the second stage, we suitably decreased the growth temperature to 710°C to grow the hierarchical structures. The surface morphology, structural and optical characterization of the grown hierarchical GaN NWs were studied by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and photoluminescence (PL) measurements, respectively. These kind of hierarchical NWs are promising to allow flat band quantum structures that are shown to improve the efficiency of light-emitting diodes.

The effect of compressive strain in buffer layer on strain relaxation and indium incorporation in InGaN multi-quantum wells (MQWs) is studied for two sets of samples grown side by side on both relaxed GaN layers and strained 10-pairs of AlN/GaN periodic multilayers. The 14-nm AlN layers were utilized in both multilayers, while GaN thickness was 4.5 and 2.5 nm in the first and the second set, respectively. The obtained results for the InGaN active layers on relaxed GaN and AlN/GaN periodic multilayers indicate enhanced indium incorporation for more relaxed InGaN active layers providing a variety of emission colors from purple to green.

Excitonic recombination dynamics in (11-22) -oriented semipolar In_0.2Ga_0.8N/In_0.06Ga_0.94N multiquantum wells (MQWs) grown on GaN/m-sapphire templates have been investigated by temperature-dependent time-resolved photoluminescence (TRPL). The radiative and nonradiative recombination contributions to the PL intensity at different temperatures were evaluated by analysing temperature dependences of PL peak intensity and decay times. The obtained data indicate the existence of exciton localization with a localization energy of E_loc(15K) =7meV and delocalization temperature of T_deloc = 200K in the semipolar InGaN MQWs. Presence of such exciton localization in semipolar (11-22) -oriented structures could lead to improvement of excitonic emission and internal quantum efficiency.

Heteroepitaxial semipolar and nonpolar GaN layers often suffer from high densities of extended defects including basal plane stacking faults (BSFs). BSFs which are considered as inclusions of cubic zinc-blende phase in wurtzite matrix act as quantum wells strongly affecting device performance. Band alignment in BSFs has been discussed as type of band alignment at the wurtzite/zinc blende interface governs the response in differential transmission; fast decay after the pulse followed by slow recovery due to spatial splitting of electrons and heavy holes for type- II band alignment in contrast to decay with no recovery in case of type I band alignment. Based on the results, band alignment is demonstrated to be of type II in zinc-blende segments in wurtzite matrix as in BSFs.

Near-field scanning optical microscopy was applied to investigate the spatial variations of extended defects and their effects on the optical quality for semi-polar (1-101) and (11-22) InGaN light emitting diodes (LEDs). (1-101) and (11-22) oriented InGaN LEDs emitting at 450-470 nm were grown on patterned Si (001) 7° offcut substrates and m-sapphire substrates by means of nano-epitaxial lateral overgrowth (ELO), respectively. For (1-101) structures, the photoluminescence (PL) at 85 K from the near surface c+ wings was found to be relatively uniform and strong across the sample. However, emission from the c- wings was substantially weaker due to the presence of high density of threading dislocations (TDs) and basal plane stacking faults (BSFs) as revealed from the local PL spectra. In case of (11-22) LED structures, near-field PL intensity correlated with the surface features and the striations along the direction parallel to the c-axis projection exposed facets where the Indium content was higher as deduced from shift in the PL peak energy.