InGaAs(N)/GaAs多層量子井的電光性研究

Abstract

本論文主要是利用光性電性的的量測，包括光激發螢光頻譜（PL）、電容電壓(C-V)、導納頻譜(C-F&G-F)、及深層能階暫態頻譜儀(DLTS)，去探討InGaAs/GaAs多層量子井結構的光電特性，主要著重在多層量子井摻入少量的氮後對於樣品會產生什麼樣的影響。 由PL 得知摻入少量的氮後，量子井的發光波長會明顯的有紅移的現象，並且量子井的侷限能力以及強度都有增強。並且摻氮的樣品，在更長波長會形成一個In-N 群聚的一個能階，而且在電性跟光性都看得出他有一個較廣的能量分佈。在摻氮以及不摻氮的樣品我們皆可以在1000nm 觀測到一個尖峰，並且藉由變功率得知是來自中隙底下的一個缺陷。當我們量測InGaAs/GaAs 不摻氮的樣品時，我們利用C-V 量測發現在-3V 低頻的時候有一個劇烈的負電容現象。 在DLTS 的量測下，我們也可以在-3V 範圍量測可以量到一個電洞放射的現象。利用一些模擬以及比較摻氮不摻氮樣品hole emission 的 time constant，我們可以判斷C-V、C-F 所量測到的負電容的現象是來自中隙底下的電洞放射照成的。

We investigate the properties of InGaAsN/GaAs multiple quantum well (MWQ) by optical and electrical measurement. This research emphasizes the properties difference between InGaAs/GaAs and InGaAsN/GaAs samples. ( N incorporation) We can observe a distinct redshift , a better confinement and stronger intensity in N incorporation InGaAsN/GaAs multiple quantum well sample. We can observe a peak at 1000nm in both InGaAs/GaAs and InGaAsN/GaAs samples,and estimate it as a trap underthe mid-gap by variate the laser’s power. In InGaAs/GaAs MQW sample, a phenomenon of NC (negative capacitance) is found from the C-V measurement under -3V and low frequency . Using some simple formulas , we know that a phenomenon of NC(negative capacitance) comes from an opposite direction of current. We can still observe a minority carrier emission under DLTS emission measurement at the same voltage, and found that it’s a trap under the midgap and it’s Ea (activation energy) just fit the 1000nm peak from PL measurement . Under some simulation and compare the N-incorporated and N-free samples we can can find the phenomenon of NC ( negative capacitance) is a hole emission below the mid-gap.