Photocurrent measurements of InGaN/GaN quantum wells under hydrostatic and uniaxial pressure

Abstract

Light emitting diode structures with InGaN quantum wells have been studied as a function of hydrostatic and uniaxial pressure (along the c-axis) under different values of reverse voltage. Photocurrent measurements (with light parallel to the epitaxial layers) allow determining energies in transverse electric (TE) and transverse magnetic (TM) polarizations, which we attribute to transitions from the heavy-hole (HH) and crystal-field split (CH) band to the conduction band. The comparison of theory and experiment suggests that the electric fields are about 25% lower than the calculated values. The transitions in TE polarization agree with the theoretical predictions, while those in TM polarization do not. In particular, the splittings between HH and CH bands are lower than the theoretical predictions.