PECULIARITIES OF HOT CARRIER TRANSPORT ACROSS GaAs p-n JUNCTIONS UNDER INTERBAND AND INTRABAND EXCITATION

In photovoltaics, the role of hot carriers is still ambiguous.Their positive role is foreseen in the potential for efficient hot carrier solar cells, while the negative one is considered only as the source of fundamental thermalization losses.In this study, hot carrier photocurrent formation was investigated in a crystalline GaAs p-n junction, which is a promising candidate for high-efficiency solar cells, under pulsed laser excitation at 0.532 µm and 1.064 µm.Timeresolved photocurrent measurements were performed at 300 K and 80 K temperatures.Hot carrier photocurrent, with polarity opposite to the electron-hole pair generation-induced current, arises in both cases, i.e., independently of photon energy, but is more pronounced under above-bandgap excitation due to much stronger interband absorption.It is shown that the effective hot carrier temperature, estimated using the temperature-coefficient model, is more effectively raised by above-bandgap radiation at lower sample temperatures.