氮化銦磊晶層之快速熱退火效應

Abstract

在本論文中，我們利用了光激螢光光譜與吸收光譜來研究氮化銦磊晶層的光學特性，並且研究快速熱退火對氮化銦磊晶層物性的影響。當氮化銦磊晶層載子濃度增加時，光激螢光光譜與吸收光譜位置會往高能量移動，此種現象為典型的Burstein-Moss 位移。此外氮化銦磊晶層光激螢光光譜其包含了電子分別與深層和淺層授子的複合放射，因此其波形是呈現高度不對稱的現象。此外從亞倫尼斯圖法可以獲得兩個活化能，其分別代表深層授子的束縛能(50 ~55毫電子伏特)與淺層授子的束縛能(5~10毫電子伏特)。 此外氮化銦磊晶層經由快速熱退火處理後，隨著退火的溫度的增加其光激螢光光譜半高寬降低、波形從不對稱趨於對稱、譜峰位置往低能量位移與積分強度增加。其中半高寬的降低與波形趨於對稱的原因為深層能階有效的經由退火處理而被抑制。此外從霍爾量測可以得知快速熱退火可有效的降低氮化銦磊晶層之載子濃度。

In this thesis, micro-photoluminescense (□-PL) and absorption were employed to investigate the optical properties of InN epilayers. The effect of rapid thermal annealing on the physical properties of InN epilayer was also studied. The PL and absorption edge of InN epilayers blueshift due to the Burstein-Moss effect when the carrier concentration increases. The photoluminescence lineshape of InN epilayer were highly asymmetry because the photoluminescence origin involved the electron to the deep and shallow acceptor transition. In addition, temperature dependence of the integrated PL intensity of InN epilayers was investigated. Two activation energies were obtained from the Arrhenius plot. We ascribe them to the binding energy of deep acceptor (Eda) (50~55 meV) and shallow acceptor (Esh) (5~10 meV), respectively. We also found that the rapid thermal annealing significantly decreases the carrier concentration of InN epilayers as well as the full width at half maximum (FWHM) of PL bands. Besides, the integrated PL intensity also increases by the RTA treatment. In our typical PL spectra, highly asymmetric line shape was observed. The emission line-shape became symmetric after the annealing treatment because the deep acceptor transition was suppressed.