裂纹对Si衬底GaN基LED薄膜应力状态的影响

Influence of Crack on Stress State of GaN Based LED on Si Substrates

本文通过XRD和PL等分析方法研究了在Si衬底生长的GaN基LED外延薄膜n型GaN层和InGaN阱层的应力状态,以及裂纹对其应力状态的影响。XRD结果表明:在Si衬底生长的GaN基LED外延薄膜n型GaN层受到张应力,在受到一定的外加应力后会以裂纹及裂纹增生的方式释放。随着裂纹数量的增加,n型GaN层受到的张应力逐渐减小,但仍处于张应力状态;n型GaN层张应力的减小使得InGaN阱层受到的压应力增大。PL分析进一步表明:InGaN阱层受到的压应力增大使得量子限制Stark效应更加明显,禁带宽度减小,发光波长表现为红移。

The influence of crack on stress relaxation behavior of GaN based LED on Si substrates was investigated by X-ray diffraction（ XRD） and photoluminscence（ PL） spectrum. XRD results showed that huge tensile stress on n-GaN layers of the GaN based LED on Si substrates was released by cracks and cracks hyperplasia. Tensile stress on n-GaN layers decreased and compression stress on InGaN layers increased as the cracks increasing. PL spectrum further showed that the increase of compression stress on InGaN layers enhanced quantum confined stark effect,and energy gap decreased,luminscence wavelength showed red shift.