Resonant Raman Scattering and Photoluminescence Emissions from Above Bandgap Levels in Dilute GaAsN Alloys

The transitions of E0 ,E0 ＋A0, and E＋ in dilute GaAs（1-x） Nx alloys with x = 0.10% ,0.22% ,0.36% ,and 0.62% are observed by micro-photoluminescence. Resonant Raman scattering results further confirm that they are from the intrinsic emissions in the studied dilute GaAsN alloys rather than some localized exciton emissions in the GaAsN alloys. The results show that the nitrogen-induced E E＋ and E0 ＋ A0 transitions in GaAsN alloys intersect at a nitrogen content of about 0.16%. It is demonstrated that a small amount of isoelectronic doping combined with micro-photoluminescence allows direct observation of above band gap transitions that are not usually accessible in photoluminescence.

GaPN混晶的瞬态发光特性

通过对GaP1-xNx混晶的瞬态发光特性的研究,揭示了在低组分下N杂质从NNi对束缚激子的特性逐渐向高组分下形成GaP1-xNx混晶的杂质带的演变。在较低组分下,样品的发光由NNi对束缚激子及其声子伴线构成,从NN1 到NN4 的衰减时间分别在 90~30ns变化。当组分提高到x^1. 3%以上时,样品的发光呈现出一个宽带,并按单指数规律衰减,辐射复合寿命大约在数十个纳秒量级,且随着N组分的增加,寿命相对减小;但在最高组分(x^3. 1% )时,其寿命仍与NN4 束缚激子的寿命相当 ( ~30ns),说明GaP1-xNx混晶新形成的杂质带仍然保持束缚激子较长的辐射复合寿命。且该杂质带低能端载流子的寿命比高能端载流子的寿命长,导致了其时间分辨谱向低能端的移动。同时在低组分样品的时间分辨谱的测量中,直接观察到了从较浅NN对束缚激子向较深NN对束缚激子的能量传输现象。