量子點紅外線偵測器之研究

Abstract

本實驗分二部分，第一部分是改變量子點長晶溫度來觀察對量子點紅外線偵測器的影響。另一部分則是改變摻雜位置來觀察其結果。 我們控制量子點的長晶溫度來改變量子點的大小及形狀。目的是為了可以觀察到在長波長波段（LWIR）的光響應。配合之前本實驗室降低暗電流的方法，在量子點之間成長高能隙的砷化鋁鎵（AlGaAs）。再改變長晶溫度來觀察其變化。發現因為長晶溫度為480 ℃的樣品在50.9K時，偵測度為9.2E9 cmHz1/2/W（-0.5V），而在較高溫77K時其偵測度為2.84E8 cmHz1/2/W（-0.6V）。而長晶溫度次高的樣品雖然偵測度沒有像前一個樣品這麼好，但是其在多個波段吸收的特性使得它可成為一溫度計。 另外我們也做了改變摻雜位置的實驗，一樣品是摻雜雜質在量子點中，而另一個是摻雜在砷化鎵的能障中。這二個樣品可以做很好的比較。摻雜在量子點中本來預期是較好的方法。此方法也的確提高光導增益。但是因不易控制雜質的均勻度使得光電流也變小了。日後我們實驗室還會繼續這個部分的研究。再嘗試不摻雜任何雜質在量子點中或能障，如此一來將有助於我們大力改善量子點紅外線偵測器的效能。

This Experiment is divided into two parts . Firstly we observed the influence of the change of growth temperature for Quantum Dots Infrared Photodetector. Secondly we observed the effect of the doping position. The size and shape of quantum dots is controlled by the growth temperature . And If we lower the growth temperature, we can get the photocurrent responsivity of the LWIR. We fabricated each sample with AlGaAs between quantum dots to decrease dark current. And we find out that the result is quite interesting. We get a multi-color QDIP when our growth temperature is 500℃, and also get a very good LWIR QDIP when the growth temperature is 480℃.A peak of Detectivity is 9.2E9 cmHz1/2/W at 14um was achieved at 50.9K. And 2.84E8 cmHz1/2/W was achieved at 77K. The performance is quite different when the doping in QDs and GaAs barrier. A higher gain is achieved when the doping position is inside the QDs. But It’s not easy to dope dopant uniformly in QDs , so the photocurrent responsivity is decreased when the dopant in inside the QDs. But it shows us the way for future work .At least we know the the dopant position is better when we dope in the GaAs barrier. In the future we can try some sample which are not doped , it will help us know which is the best way to dope the QDIP. Thus we can improve the performance of QDIP.