Optical studies of semiconductor heterostructures

• Main Authors: Tzu-Ping Chen, 陳自平
• Other Authors: Jhih-Lin Shen
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/48130430619752008602

碩士 === 中原大學 === 應用物理研究所 === 90 === ABSTRACT Contactless electroreflectance(CER) and photoluminescence(PL) measurements were used to study the structural properties of Ho-doped InGaAsP epilayers and InGaN/GaN multiple quantum wells(MQWs) light emitting devices(LEDs). The broadening parameter of the InGaAsP band-to-band transition at 14 K was found to decrease from 0~0.110 wt%. A strain-induced splitting of the valence band in Ho-doped InGaAsP layers has been found in CER spectra at 110 K. The red-shift of transition energy in the temperature range 14~300 K was fitted by Varshni relation and O’Donnell formula. The InGaN/GaN MQWs LEDs with In content about 18~20 wt% was analyzed with temperature dependent CER. Two regions of transition energy were found in different temperature ranges. This sample was also measured by time-resolved photoluminescence(TRPL). The time decay of transition intensity at lower energy is slower than that at higher energy. The decay time of PL increases with In concentration. The FWHM of PL spectra increases with In concentration. These results were interpreted in terms of localization induced by inhomogeneous In concentration.