Blue-green and blue stimulated emission under photopumping in Zn0.8Cd0.2Se-ZnSe and ZnSe-ZnS multiple quantum wells (MQWs) on (100) GaAs substrate grown by atmospheric pressure metalorganic chemical vapor deposition (AP-MOCVD) have been investigated, respectively. For the Zn0.8Cd0.2Se-ZnSe MQWs, the stimulated emission of the sample with different cavity length is observed at 77K, two groups of stimulated emission lines observed are attributed to n equals 1 heavy- hole (hh) and light-hole (lh) exciton transition, respectively, and it is noticed that the sample with the shorter Fabry-Perot cavity length has the larger threshold excitation and more mode spacing. For the ZnSe-ZnS MQWs, the blue stimulated emission is observed and attributed to the exciton-exciton interactions.
At high excitation intensity the photoluminescence (PL) spectra of ZnCdSe/ZnSe multiple quantum wells were studied, which showed strong excitonic emission and a broad emission band at low energy side. The dependence of the broad emission band on excitation intensity shoed obviously that the broad emission band is related to impurity. In time resolved luminescence spectra, with increasing the delay times (ns), the broad emission band shifts to low energy side and full width at half maximum decreased, which showed the typical characteristic of donor-acceptor pairs (DAP) emission. And then, the reason that the excitonic emission peak and the DAP band decay with same speed was discussed and it was attributed to the free carriers relax effect.
The transformation from stimulated to spontaneous emissions at 77K is performed in Zn0.8Cd0.2Se-ZnSe strained layer superlattice (SLS) with Fabry-Perot cavity. It is found that the lasing oscillation modes disappear and the stimulated emission is transformed into the amplified spontaneous emission owing to the phase space filling effect of exciton states under higher excitation density.
The band edge nonlinear absorption in ZnTe/CdZnTe multiple quantum wells (MQWs) is studied at room temperature. It is found that the exciton absorption peak tends to saturate, broaden and the absorption edge shift to lower energy side with increasing of pump intensities. The optical bistability in ZnTe/CdZnTe MQWs optical bistable device is investigated on transmission at room temperature. The research result indicates that the threshold and contrast ratio for the optical bistability in ZnTe/CdZnTe MQWs optical bistable device are about 292.5 kW/cm2 and 3:1, respectively.
The stimulated emission with multimode structure from the n equals 1 heavy exciton was observed in a Zn0.8Cd0.2Se-ZnSe strained layer superlattice at 77K. It is found that the different modes have different half widths of the time delay curves, depending on the different threshold for each model. Therefore, the threshold relation can be qualitatively obtained in terms of the half width of the time delay curve.
Photoluminescence (PL) measurement of ZnCdSe-ZnSe strained layer superlattices structures subjected to an electric field has been performed. As well as the shifts of the PL energy, the main peak, due to the exciton emission was shifted to the lower energy side with increasing electric field. The reason is related to the field-induced electron-hole separation in the ZnCdSe well.
The picosecond optical bistability of Zn1-xCdxSe/ZnSe (x equals 0.23) multiple quantum well (MQW) has been observed by a Streak Camera at room temperature for the first time. In the absorption spectra of ZnCdSe/ZnSe MQW, there are two peaks at 515 nm and 530 nm. We discussed the origin of the two peaks and physical mechanism of the bistability.
We have measured the nonlinear absorption change in ZnSe thin films at 77 K. The nonlinear mechanisms are attributed to the combination of the increasing absorption and the bleaching of excitons.
Excitonic properties of ZnSe1-xSx epilayer fabricated on GaAs substrate by a Ap-MOCVD have been investigated. Luminescence, excitation, and time-resolved spectroscopy have been employed to study the interaction between excitons and electrons at 77 and 300 K. Under pulsed N2 laser excitation it is found that the peak shift of the near band edge emission is large, especially at room temperature. This is because the bottoms of the conduction bands are filled at higher temperature and the carriers from the exciton-exciton scattering must occupy higher energy levels. Therefore a shift of the peak toward lower energy is expected.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.