摘要
利用变温光致发光(PL)谱及时间衰退发光谱研究了一系列CaP_(1-x)N_x混晶的光学性质。GaP_(1_x)N_x混晶的PL谱从低组分的NN对束缚激子及其声子伴线到高组分杂质带发光的特征,表现出明显的带降降低的趋势。测量结果显示,在组分x≥0.24％的样品的发光谱中NN_1能量之下已经开始出现几个新的束缚态,对其激活能的拟合及对时间衰退发光谱的分析表明,新的束缚态一方面仍保留有N束缚激子的性质,另一方面又表现出有别于NN对束缚激子的发光机制。说明新的束缚态有可能由新的N原子组成(如NNN原子)或与NN对束缚激子存在着某种相互作用。
GaP_(1-x)N_x alloy is a remarkable and promising semiconductor for its giant band-gap bowing effect
and its potential application in optoelectronic devices. In this article, we carried out a series of studies on the
optical properties of GaP_(1-x)N_x alloys, especially focusing on the samples with composition x=0.24%, 0.6%,
0.81%, using temperature-dependent photoluminescence(PL) speetra and transient photoluminescense spectra. At
17 K PL spectra, the GaP_(1-x)N_x alloys exhibit an obvious tendency of band-gap reduction with increasing composi-
tion x. When composition x<0.24%, the NN_1 zero-phonon line and its replicas in GaP_(1-x)N_x alloys are well re-
solved, displaying similar characteristic to dilute nitrogen doped GaP; while 0.24%<x<0.81%, the PL peak
energy red-shift effect continues and the emission intensity of the NN_1 replica region is enhanced relative to the cor-
responding zero-phonon line due to the carriers transferring effect with increasins composition x. In addition, the PL
linewidth broadens and the fine structure is gradually illegible. At higher compositions, the PL spectra shift to lower
energy and become wide band emission with long emission tail. The fit to the spectra profiles confirm that several
new bound states exist below the energy of NN_1 zero-phonon line even when the composition is as low as 0.24%,
where the phonon replicas are apparently legible, but the energy of the new bound states might superimpose with the
NN_1 phonon replicas. At higher composition (x=0.43%, 0.6%), the new bound states and the carriers transfer-
ring effect are more obvious. While at x=0.81%, it is hard to distinguish the energy position of each bound state,
indicating a trend from doping bound states to impurity band. Such trend suggests a lower critical point from bound
states to impurity band vompared with references. The activation energy of the new bound stat
出处
《发光学报》
EI
CAS
CSCD
北大核心
2004年第2期168-172,共5页
Chinese Journal of Luminescence
基金
国家自然科学基金(60276002)
福建省自然科学基金(A0110007)
