本論文使用學長製作出的氮化鎵光電晶體光偵測器，量測出其暗電流(Dark current)、外部量子效應(EQE)、計算出響應率、響應時間、響應的雜訊以及不同光強度下的電壓訊號。量測的元件為n-p-i-n結構光電晶體光偵測器，以商業用LED結構晶圓(AlGaInN based)，利用矽擴散的方式，將最上層的p-AlGaN反轉成n-AlGaN，使晶圓結構從原本的p-i-n結構變成n-p-i-n結構。
n-p-i-n光電晶體光偵測器的元件在峰值波長382 nm，入射光強度為15.6 μW/cm2，當逆向偏壓VCE為1 V時，峰值的外部量子效率可以達到大於16600%，對應的響應率大於51.4 A/W；當逆向偏壓VCE為3 V時，峰值的外部量子效率更可以達到大於38000%，對應的響應率大約為117.7 A/W，截止波長約為415 nm。對於響應時間的量測，我們在固定波長382 nm、頻率為5 Hz、逆向偏壓VCE為3 V時，量測到其上升時間(Rise time)為15.8 ms，下降時間(Fall time)為83.3 ms，對於大部分的應用都是可行的。因此我們使用商業用LED結構晶圓成功製作了UV-A光電晶體光偵測器，達到低成本、製程簡單的目的，並且可在低偏壓下得到相當高的響應率，證明這種設計是相當可行的。

In this paper, we characterized the GaN based phototransistors which made by seniors, including the dark current, external quantum efficiency (EQE), response speed, response time, noise of the phototransistor and the photocurrent versus incident light intensity. Instead of using a wafer with a bipolar junction transistor n–p–n epitaxial structure, we successfully fabricated AlGaInN-based near-ultraviolet (UV) heterojunction phototransistors (HPTs) on a commercial wafer with a light-emitting-diode (LED) epitaxial structure by employing silicon diffusion to convert a part of the p-AlGaN layer into an n-AlGaN layer.
The device was emitter-side illuminated using an incident light intensity of 15.6 μW/cm2 at the fixed wavelength of 382 nm at which the responsivity was the highest. The EQE and responsivity were approximately 16600% and 51.4 A/W when VCE was 1V at 382 nm, respectively. It then increased the V¬CE of up to approximately 3 V, the peak EQE value of 38000% at 382 nm, corresponding to a responsivity 117.7 A/W. The cutoff wavelength was approximately 415 nm which was determined by the minimum bandgap energy of the MQWs. The response speed of our HPT was illuminated with the same condition like EQE, and the VCE¬ was set at 3 V. The dominating factor affecting the response speed was the fall time, which was measured to be approximately 85 ms and the rise time was approximately 15.8 ms, which might be acceptable for most applications. The results implied the potential to integrate an LED with a phototransistor monolithically and cost effectively.

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