Identification of the active photo-excited carrier in reverse biased quantum dot resonant tunneling diode

The active photo-excited carrier has been identified in reverse biased quantum dot resonant tunneling diode (QDRTD) for light detection. The QD is embedded on the AlAs/GaAs/AlAs double barrier part of the material structure and is found with strong charge memory effect. The QD is charged with electrons in forward bias and the charge storage of QD is maintained well in reverse bias until the voltage of QD resonant tunneling peak. With this charge memory effect, the photo-excited holes are charged into QDs in forward bias and still influence the reverse bias behavior of QDRTD at dark. Compared to the illuminated QDRTD in reverse bias, the active photo-excited carrier of reverse biased QDRTD is unambiguously identified as photo-excited holes. The potential profile of QDRTD structure is also calculated and the potential near charged QDs is found greatly pushed up above GaAs EC. This may explain the trapping of photo-excited hole by QD for QDRTD in reverse bias.