蕭特基紫外光偵測器製作於獨立式氮化鎵基板上之研究

Abstract

本實驗主要想探討的是，在不同基板上製作蕭特基紫外光偵測器的差別。本實驗使用兩種基板：一組是用MOCVD製作的約2微米厚的氮化鎵薄膜；以及利用HVPE成長300微米厚的獨立式氮化鎵基板，先量測此兩種基板的光學及電性與晶格品質差異性後，再探討製作於其上的元件有何不同的地方，包含了逆向偏壓下的漏電流大小以及光偵測器的鑑別度等。我們也利用同樣的獨立式氮化鎵基板，比較橫向與縱向電極蕭特基元件的差別。此外，對氮化鎵蕭特基元件，進行熱退火的研究，找出最適當的元件設計。

In this thesis, the high quality thick GaN substrates had been grown and characterized by Hydride Vapor Phase Epitaxy (HVPE). Then, the Schottky barrier photodetectors with freestanding GaN substrates were fabricated. This thesis is made up of two parts. In the first part, we focused on the difference between the schottky diodes prepared on the 2μm-thick GaN substrates by MOCVD and 300μm-thick GaN substrates by HVPE. It was found that leakage current of the PDs prepared on freestanding GaN substrate was significantly smaller due to the improved crystal quality. In the second part, we reported the fabrication of verticle photodetectors (PDs) on freestanding GaN substrate. Compared with the lateral PD prepared on the same substrate, We found the vertical PDs had smaller leakage current. It was also found that we can reduce the photoconductive gain and enhance ultraviolet-to-visible rejection ratio by using the vertical PDs with freestanding GaN substrates.