Intensity-dependent photoluminescence studies of the electric field in N-face and In-face InN/InGaN multiple quantum wells

We probe the electric field in In-face and N-face InN/InGaN multiple quantum wells (MQWs) using low temperature intensity-dependent photoluminescence (PL) under continuous-wave laser excitation at 900 nm. The In-face structure consists of 30 periods of 2.5 nm thick InN wells and 24 nm thick In0.92Ga0.08N barriers. The N-face sample consists of 25 periods of 1.5 nm InN wells and 15 nm thick In0.88Ga0.12N barriers. At low excitation power, the PL peak energy from both In-face and N-face MQWs is redshifted relative to that from bulk InN. As excitation power increases, we observe a 50 and 44 meV blueshift of the PL peak energy from the In-face and N-face MQWs, respectively. The blueshift is a result of the optically induced screening of the built-in electric field. From the measured blueshift, we calculate a minimum change of the electric field to be ∝0.4 MV/cm and ∝0.6 MV/cm in the In-face and N-face well regions, respectively. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)