具低溫成長氮化鎵覆蓋層之氮化鋁鎵/氮化鎵蕭基二極體紫外光偵測器

本實驗主要研究一具有低溫成長氮化鎵覆蓋層之氮化鋁鎵／氮化鎵蕭基二極體紫外光偵測器，除此之外我們也製作了一組傳統的氮化鋁鎵／氮化鎵蕭基二極體紫外光偵測器作為對照組。其中低溫成長氮化鎵覆蓋層的成長溫度為550℃，且即使經過1050℃，10分鐘的熱處理，其材料結構與電特性仍然沒有明顯的改變。由實驗結果發現，具有低溫成長氮化鎵覆蓋層之紫外光偵測器的漏電流有明顯降低的趨勢，此現象也造成元件之光電流與漏電流的比值較高。另外，當入射光波長為320nm且外加偏壓為-1V時，具有低溫成長氮化鎵覆蓋層之氮化鋁鎵／氮化鎵蕭基二極體紫外光偵測器及傳統之氮化鋁鎵／氮化鎵蕭基二極體紫外光偵測器的光響應度（responsivities）分別為0.015 A/W與0.03 A/W。

AlGaN/GaN photodetectors (PDs) with and without the low temperature (LT) GaN cap layer were both fabricated. It was found that no property change in LT GaN could be observed even with a 1050°C post growth thermal annealing. It was also found that we could use the LT GaN layer to significantly reduce the leakage current of the PDs and thus achieve a much larger photocurrent to dark current contrast ratio. With incident light wavelength of 320 nm and a 1 V reverse bias, the measured responsivities were around 0.03 and 0.015 A/W, respectively, for the AlGaN/GaN PDs with and without the LT GaN cap layer.