Quantitative analysis of the polarization fields and absorption changes in InGaN/GaN quantum wells with electroabsorption spectroscopy

Electroabsorption measurements are reported for wurtzite InGaN/GaN quantum wells. The electroabsorption technique allows exact quantitative analysis of absorption and absorption changes in InGaN quantum wells and barrier layers, with recorded field-induced absorption changes as large as 7000 cm−1 below and almost 20000 cm−1 above the band edge. The technique thus allows precise determination of the strong internal fields that originate from strain-induced polarization and differences in spontaneous polarization. The fields measured on functioning diodes vary between 1.1 and 1.4 MV/cm for indium concentrations in InGaN quantum wells ranging from 7% to 9%.