Enhancement of photocurrent in InGaN/pseudo-AlIGaN multi quantum wells by surface acoustic wave

摘要

In this work, we have investigated the variation of internal electric field of 4-period In_(0.16)Ga_(0.84)N/pseudo-AlInGaN multiquantumwells (MQWs) embedded in p-i-n structure by surface acoustic waves (SAWs). The pseudo-AlInGaN barriersconsist of two In_(0.16)Ga_(0.84)N(11 Å) sandwiched by three Al_(0.064)Ga_(0.936)N (15 Å). The equivalent indium and aluminumcompositions in pseudo-AlInGaN barrier are 0.043 and 0.052, respectively, which can be calculated by volume ratio. Forreference purpose, In_(0.16)Ga_(0.84)N/GaN MQWs was also used. To generate surface acoustic wave, interdigital patterns with1 μm finger width were fabricated by e-beam lithography. The piezoelectric fields for GaN barrier and pseudo-Al_(0.043)In_(0.052)Ga_(0.905)N barrier samples are found to be 1.5 MV/cm, 0.33 MV/cm from bias-PL. From μ-PL measurementfor pseudo-Al_(0.043)In_(0.052)Ga_(0.905)N barrier sample, we observed lowest luminescence intensity at 100 MHz and 13 dBm inradio frequency (RF) generator, which means that electron-hole recombination can be suppressed by SAWs. ThePhotocurrent measurement for pseudo-Al_(0.043)In_(0.052)Ga_(0.905)N barrier sample was observed increasing around 2 orders ofmagnitude at 100 MHz when compare to GaN barrier sample. Based on our results, the reduced piezoelectric field addedto SAWs can be provided one of the solutions for enhancing photocurrent in Ⅲ-nitride photovoltaic devices by extractcarriers from quantum wells easily and enhancing traveling length of carriers.