Tailored carrier escape rates in asymmetric double quantum wells

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Abstract
An experimental study of carrier escape in a series of p - i - n asymmetric double quantum well (ADQW) structures using time-resolved photoluminescence is presented. By performing complementary continuous-wave photoluminescence and photocurrent measurements the carrier escape times were extracted as a function of temperature and perpendicular applied electric field and compared with a quantitative model which includes the mechanisms of tunnelling, thermally assisted tunnelling and thermionic emission. Holes were found to dominate the escape rate, and in the light of this it is shown that if narrow wells are grown next to wider wells and nearer the p region a significantly enhanced carrier escape rate can result. This is explained by resonant hole tunnelling and may have implications in the design of QW modulator and solar cell devices with improved performance.