Papers by Keyword: Multiple Quantum Wells

Abstract: A serious of non-polar a-plane AlGaN-based multiple quantum wells (MQWs) were successfully grown on the semi-polar r-plane sapphire substrate with metal organic chemical vapor deposition technology. Intense MQWs-related emission peaks at an emission wavelength covered from 277-294 nm were observed based on the photoluminescence measurement. It was found that the employment of the trimethyl-aluminum (TMAl) flow duty-ratio modulation method which was developed based on the two-way pulsed-flows growth technique played a crucial role to control the Al composition of the non-polar a-plane AlGaN epi-layers. The non-polar a-plane AlGaN-based MQWs were deposited with the new developed TMAl flow duty-ratio modulation technique. Evident-3th order X-ray diffraction (XRD) satellite peak was observed from the high resolution-XRD measurement, proving the successful growth of non-polar a-plane AlGaN-based MQWs with abrupt hetero-interfaces.

Abstract: The structural and optical properties of InxGa1-xN/GaN multi-quantum wells (MQWs) grown on sapphire are discussed. Two kinds of InxGa1-xN/GaN MQWs with same period and different single cycle thickness and different growth temperature of MQWs are selected. Firstly, from the result of SRXRD and RBS/C, we can estimate that indium content of InxGa1-xN /GaN MQWs is 0.033 and 0.056, the single cycle thickness of MQWs is 13.04nm and 15.86nm respectively. Secondly the PL results indicate the optical properties of InxGa1-xN/GaN MQWs. Finally, we find indium content decreasing with increasing growth temperature of MQWs and the emission intensity reducing with temperature increasing, the emission optical peak position versus temperature show the “S-shaped” character. All these experimental results testify the material design of InxGa1-xN/GaN MQWs will have potential applications in spectral LED.

Abstract: Luminescence properties of blue emission InGaN/GaN multiple quantum well (MQW) have been studied by temperature dependent photoluminescence (PL), photoluminescence excitation (PLE) and time-resolved photoluminescence (TRPL) spectroscopic techniques. Two typical samples are studied, both consisting of five periods of InGaN wells with different indium compositions of 21% and 24%, respectively. According to the PL and PLE measurement results, large values of activation energy and Stokes’ shift are obtained. This indicates that higher Indium composition results in an increase of composition fluctuation in the InGaN MQW region, showing the stronger carrier localization effect. The lifetime at the low-energy side of the InGaN peaks is longer for higher indium composition, as expected from the larger Stokes shift.