Graded Barrier for Photovoltaic Operation of p-type GaAs/AlGaAs Heterostructure*

In developing of Infrared detection devices, the photovoltaic devices have significant advantages over photoconductive detectors since they operate at zero bias. These also have lower operating powers as well as reduced low frequency noise. We have tested undoped AlGaAs (constant barrier) /p-type GaAs (emitter) / undoped AlGaAs (graded barrier) structures as photovoltaic detectors in the infrared region. A photovoltaic responsivity of 450 mV/W was obtained with a specific detectivity (D*) of 1.5 $\times $ 10$^{6}$ Jones at a peak wavelength 1.8 $\mu $m at 300 K. The photovoltaic response originates due to the charge accumulation at the contact region, resulted by the unidirectional net carrier flow forced by the graded barrier. The response region can be altered or broadened by sandwiching different materials or multiple materials between the two barriers. In addition to IR detectors, this technique can also be implemented on developing an efficient solar cell.