The electroluminescence （EL） and photoluminescence （PL） spectra of InGaN/GaN multiple quantum wells （MQWs） with a prestrained InGaN interlayer in a laser diode structure are investigated. When the injection current increases from 5 mA to 50 mA, the blueshift of the EL emission peak is 1 meV for the prestrained sample and 23 meV for a control sample with the conventional structure. Also, the internal quantum efficiency and the EL intensity at the injection current of 20 mA are increased by 71% and 65% respectively by inserting the prestrained InGaN interlayer. The reduced blueshift and the enhanced emission are attributed mainly to the reduced quantum-confined Stark effect （QCSE） in the prestrained sample. Such attributions are supported by the theoretical simulation results, which reveal the smaller piezoelectric field and the enhanced overlap of electron and hole wave functions in the prestrained sample. Therefore, the prestrained InGaN interlayer contributes to strain relaxation in the MQW layer and enhancement of light emission due to the reduction of QCSE.
The influence of the width of a lattice-matched A10.82In0.18N/GaN single quantum well （SQW） on the absorption coefficients and wavelength of the intersubband transition （ISBT） has been investigated by solving the Schr5dinger and Poisson equations self-consistently. The wavelength of 1-2 ISBT increases with L, the thickness of the single quantum well, ranging from 2.88 ~m to 3.59 ~.m. The absorption coefficients of 1-2 ISBT increase with L at first and then decrease with L, with a maximum when L is equal to 2.6 nm. The wavelength of 1-3 ISBT decreases with L at first and then increases with L, with a minimum when L is equal to 4 nm, ranging from approximately 2.03 p^m to near 2.11 p.m. The absorption coefficients of 1-3 ISBT decrease with L. The results indicate that mid-infrared can be realized by the A10.s2In0.1sN/GaN SQW. In addition, the wavelength and absorption coefficients of ISBT can be adjusted by changing the width of the SQW.
