CAJ | 학술논문

我们利用光荧光(PL)以及时间分辨光谱(TRPL)研究了用MBE生长在GaAs衬底上的GaNAs/GaAs量子阱的激子局域化以及退局域化.研究发现,在低温下用连续光(Cw)激发,由于GaNAs中势振荡所产生的局域激子发光是所测量到光谱的主要发光来源.然而在脉冲激发下,情况完全不同.在高载流子密度激发或者高温下GaNAs/GaAs量子阱中例外,一个高能端的PL峰成为了主要的发光来源.通过研究,我们将这个新的发光峰指认为量子阱中非局域激子复合的PL峰.这个发光峰在温度和激发强度的变化过程中与局域激子相互竞争.我们相信这一过程也是许多文献所报道的在InGaN和AlGaN等氮化物中经常观测到的发光峰位随温度"S"形变化的主要根源.
아문이용광형광(PL)이급시간분변광보(TRPL)연구료용MBE생장재GaAs츤저상적GaNAs/GaAs양자정적격자국역화이급퇴국역화.연구발현,재저온하용련속광(Cw)격발,유우GaNAs중세진탕소산생적국역격자발광시소측량도광보적주요발광래원.연이재맥충격발하,정황완전불동.재고재류자밀도격발혹자고온하GaNAs/GaAs양자정중예외,일개고능단적PL봉성위료주요적발광래원.통과연구,아문장저개신적발광봉지인위양자정중비국역격자복합적PL봉.저개발광봉재온도화격발강도적변화과정중여국역격자상호경쟁.아문상신저일과정야시허다문헌소보도적재InGaN화AlGaN등담화물중경상관측도적발광봉위수온도"S"형변화적주요근원.
We have studied exciton localization and delocalization effect in GaNAs/GaAs quantum wells (QWs) grown by molecular beam epitaxy (MBE) using photoluminescence (PL) and timeresolved PL measurements. Studied results suggest that, at low temperature and under a conventional CW excitation, measured PL spectra were dominated by localized exciton (LE) emission caused by potential fluctuations in GaNAs layer. However, under short pulse laser excitation, it is different. An extra high-energy PL peak comes out from GaNAs/GaAs QWs and dominates the PL spectra under high excitation and/or at high temperature. By investigation, we have attributed the new PL peak to the recombination of delocalized excitons in QWs. This recombination process competes with the localized exciton emission, which, we believe, constitutes the "Sshaped" temperature-dependent emission shift often reported in ternary nitrides of InGaN and A1GaN in the literature.