InGaN/GaN多量子阱蓝光LED外延片的变温光致发光谱

Temperature-dependent Photoluminescence Spectra of InGaN/GaN Multiple Quantum Wells Blue LED Wafers

利用MOCVD在Al2O3(0001)衬底上制备InGaN/GaNMQW结构蓝光LED外延片。以400mW中心波长405nm半导体激光器作为激发光源,采用自主搭建的100~330K低温PL谱测量装置,以及350~610K高温PL测量装置,测量不同温度下PL谱。通过Gaussian分峰拟合研究了InGaN/GaNMQW主发光峰、声子伴线峰、n-GaN黄带峰峰值能量、相对强度、FWHM在100~610K范围的温度依赖性。研究结果表明:在100~330K温度范围内,外延片主发光峰及其声子伴线峰值能量与FWHM温度依赖性,分别呈现S与W形变化;载流子的完全热化分布温度约为150K,局域载流子从非热化到热化分布的转变温度为170~190K;350~610K高温范围内,InGaN/GaNMQW主发光峰峰值能量随温度变化满足Varshni经验公式,可在MOCVD外延生长掺In过程中,通过特意降温在线测PL谱,实时推算掺In量,在线监测外延片生长。以上结果可为外延片的PL发光机理研究、高温在线PL谱测量设备开发、掺In量的实时监测等提供参考。

A blue light LED epitaxial wafer with InGaN/GaN MQW structure was prepared on an Al2O3 (0001) substrate by MOCVD. The 400 mW semiconductor laser with a center wavelength of 405 nm was used as the excitation light source. The PL-spectrum at different temperatures was measured by the self-built 100-330 K low-temperature PL spectrum measurement device and the 350-610 K high-temperature PL measurement device. The peak energy and the relative intensity of InGaN/GaN MQW main luminescence peak,the phonon concomitant peak and the n-GaN yellow band peak,as well as the temperature dependence of the FWHM in the range of 100-610 K were studied by Gaussian peak differentiating and imitating. The results showed that in the temperature range of 100-330 K,the peak energy of the main luminescence peak and the phonon concomitant peak of the epitaxial wafer,as well as the temperature dependence of the FWHM displayed S and W-shaped changes respectively;the complete heating distribution temperature of the carrier was about 150 K;the transition temperature of local carriers from non-heating to heating distribution was 170-190 K;in the high temperature ranged 350-610 K,the changes in peak energy of InGaN/GaN MQW with temperature variation satisfied the Varshni empirical formula. In the In-doped process of MOCVD epitaxial growth,the PL spectrum could be measured by deliberately cooling the temperature;the amount of In-doped was calculated in real time;and the epitaxial wafer growth was monitored online. The above results can be used for the study of PL luminescence mechanism of epitaxial wafers,development of high-temperature online PL spectrum measurement equipment,real-time monitoring of In-doped and so on.