荧光法测定半导体禁带宽度

Luminescence measurement of band gap

光学带隙或禁带宽度是半导体材料的一个重要特征参数.本文以3个具有代表性的InGaN/GaN多量子阱结构作为研究对象,深入探讨了荧光法测定某个目标温度下InGaN阱层的光学带隙所需要满足的测试条件.由于InGaN阱层是一种多元合金且受到来自GaN垒层的应力作用,所以该阱层中不仅存在着杂质/缺陷相关的非辐射中心,也存在着组分起伏诱发的局域势起伏以及极化场诱发的量子限制斯塔克效应.因此,为了获得目标温度下InGaN阱层的较为精确的光学带隙,提出了荧光测量至少应满足的测试条件,即必须消除该目标温度下非辐射中心、局域中心以及量子限制斯塔克效应对辐射过程的影响.

Optical band gap or band gap is an important characteristic parameter of semiconductor materials.In this study,several representative InGaN/GaN multiple quantum well structures are taken as the research objects,and the test conditions that need to be met for the luminescence measurement of the optical band gap of the InGaN well layer at a certain target temperature are discussed in depth.Since the InGaN well layer is a multi-element alloy and is subjected to stress from the GaN barrier layer,there exist not only impurity/defect-related non-radiation centers in the well layer,but also localized potential fluctuation induced by composition fluctuation and quantum confinement Stark effect(QCSE)induced by polarization field.Therefore,in order to obtain a more accurate optical band gap of the InGaN well layer,we propose the following test conditions that the luminescence measurement should meet at least,that is,the influence of the non-radiation centers,the localized centers and the QCSE on the emission process at the target temperature must be eliminated.Although these test conditions need to be further improved,it is expected that this test method can provide valuable guidance or ideas for measuring the semiconductor optical band gap.