We report extremely efficient and fast (approximately 25 pS FWHM) escape times of optically generated carriers in a reverse biased GaAs/AlGaAs graded index separate confined heterostructure single quantum well (GRINSCH-SQW) laser. Room temperature photoconductivity (PC) measurements in a high speed ridge waveguide detector are compared with time resolved photoluminescence (PL) measurements at T $EQ 20 K, 70 K, and 150 K. By comparing the experimental PL and PC response times and efficiencies as a function of bias voltage and temperature with theory, we show that the results are consistent with a simple model based on electron recombination and escape out of the quantum well. Electron escape occurs by either direct tunneling out of the lower electronic level, by thermally assisted tunneling out of the upper weakly bound state, or by thermionic emission over the barrier, depending on the bias voltage and temperature.
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