A tunable hot-electron light emitter
We demonstrate the operation of a novel tunable wavelength surface emitting device. The device is based on a p-GaAs and heterojunction containing an inversion layer on the p-side, and GaAs quantum wells on the n-side, and is referred to as HELLISH-II (hot-electron light emitting and lasing in semiconductor heterojunction). The device utilizes hot-electron longitudinal transport and, therefore, light emission is independent of the polarity of the applied voltage. Because of this symmetric property, the device can perform light logic functions. The wavelength of the emitted light can be tuned with the applied bias from GaAs band-to-band transition in the inversion layer to e1 - hh1 transition in the quantum wells. The operation of the device requires only two diffused in point contacts. Therefore, a two-dimensional array of surface emitters can be fabricated very cheaply and easily. Theoretical modelling of the device operation is carried out and compared with the experimental results. An optimized structure for high-efficiency device operation, as based on our model calculations, is also proposed.