Photoconductance measurements and Stokes shift in InGaN alloys

We report the results of photoluminescence (PL), transmission and photocond uctance (PC) studies of InxGa1-xN alloys grown by metalorganic chemical vap or deposition (MOCVD) or molecular beam epitaxy (MBE). First, we demonstrat e that PC measurements allow to determine the gap energy and give the same value as transmission experiments in the case of thin InGaN layers. Second, we have performed PL and PC measurements in thin InGaN films. The comparis on between the PL peak and PC measurements gives the Stokes shift. We study the Stokes shift as a function of temperature, and explained it in terms o f localization and Burstein - Moss effect. Finally, we show that our measur ements can be extended to the case of InGaN/GaN quantum dots. (C) 2001 Else vier Science B.V. All rights reserved.