MOVPE生长的InGaN/GaN单量子阱的光致发光和光吸收特性

研究了用金属有机物气相外延(MOVPE)法在蓝宝石衬底上生长的In组分浓度保持不变的InGaN/GaN单量子阱结构在室温下的发光特性和光吸收特性.实验结果表明,在InGaN厚度<3nm时,随着样品InGaN势阱层宽度的增加(1nm),光致发光(PL)谱的发光峰值波长出现明显的红移33nm现象,而且发光强度下降8%,谱线半峰全宽(FWHM)展宽,通过对样品的透射、反射光谱研究发现,量子阱层窄(1.5nm)的样品在波长接近红外区时出现无吸收的现象,即R+T达到了100%,而在阱层较宽的样品中没有发现这一现象,对引起这些现象的原因进行了讨论.这些结果有助于开发和优化三族氮化物半导体光电器件的进一步研究工作.

Photoluminescence and Optical Absorption Properties of InGaN/GaN Single Quantum Well Grown by MOVPE

Gallium nitride and its ternary alloys have been attracting much attention because of their unique physical and chemical properties and their great potentialities for semiconductor industrial applications, such as light emitting diodes(LEDs), laser diodes(LDs) operating from green to ultraviolet(UV), UV-detectors and microwave power devices. The primary object of this study is to investigate the influence of different thickness of Fixed-Indium-Content InGaN layer on the shift of the photoluminescence(PL) spectra and optical absorption of the whole system structure. Photoluminescence(PL) and absorption properties of the Fixed-Indium-Content InGaN/GaN heterojunction single quantum well (SQW) structures have been investigated using photoluminescence spectrum and ultraviolet-vi-sible spectrophotometer at room temperature, respectively. The films were grown by metal-organic vapor phase epitaxy (MOVPE), using GaN buffer layer on sapphire substrates. The width of InGaN layer (＜3 nm) in the SQW was varied while keeping other growth parameters fixed. Sample A has an InGaN active layer of thickness 1.5 nm, and Sample B has an InGaN active layer of thickness 2.5 nm. Two samples were capped with a 25 nm GaN layer. PL measurements show that the PL peak position (432 nm in Sample A and 465 nm in Sample B) was redshifted by 33 nm, the intensity was reduced about 8%, and the full width at half maximum (FWHM) of PL spectrum increases with increasing (1 nm) of the potential well layer width. The spectra of transmission and reflection show that transmission T is very high there can be only few reflection R as no absorption R+T exceeds 100% in the near infrared ranges for the sample with InGaN layer of thickness 1.5 nm. The reasons of these results are discussed. The significance of these studies is multifold and these results provide further information of importance toward the design optimization of optoelectronic devices employing the Ⅲ-nitrides.