Persons

The influence of the excess holes capture efficiency on the carrier collection process with an increasing photoexcitation in quantum wells of n -AlGaAs/GaAs heterostructures has been studied. It has been shown that the influence of the ratio of photoluminescence intensities from quantum well and from barrier layers on the quantum well width has an oscillating form. The hole capture times in the maximum and the minimum of the oscillations have been estimated (3 psec and 370 psec, respectively). The energy transition shift in resonant quantum well at high excitation densities has been explained by the «charge buildup effect» due to the difference between the capture efficiencies of the electrons and holes.

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The process of excess current carriers capture from broad-zone barrier layers into the quantum well is critical in operation of such devices based on the semiconductor heterostructures, as lasers, light diodes, photodetectors. The oscillating dependence of the capture rate on the quantum well width experimentally has been not enough studied. The aim of the present study is to clarify the effect of oscillations of the holes capture efficiency depending on the quantum well width on the temperature behavior of photoluminescence (PL) in modulation-doped n-AlGaAs/GaAs heterostructures. The temperature measurements of integral PL intensity of the structures with quantum wells of different thicknesses corresponding to different holes capture (under the condition of resonant capture and without it) have been carried out. It has been shown that the holes capture efficiency influences not only on the PL intensity value, but, also, on its temperature dependence. In the low-temperature range (77–140 K) the PL intensity in a resonant structure becomes lower with the temperature increase more rapidly than that in the structures with slow capture. Such a difference is explained by the following. The holes capture rate under the resonance conditions is so high, that its change with the temperature already does not affect the PL intensity value and the temperature weakening of PL is associated only with the decrease of the radiative recombination efficiency β in a quantum well. In the nonresonant structures the temperature behavior of PL depends not only on the quantum efficiency β, but, also, on the local holes capture rate, which increases with the temperature growth. The results obtained present interest for optimization of heterostructure parameters during the design of the devices, in operation of which the excess carriers capture efficiency into the quantum well plays a decisive role.

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