Characterization and simulation of photodetector sensing elements based-on heterojunction and heterodimensional devices

In this paper, we deal with the properties of a family of optical devices based on heterojunction and heterodimensional structures, and investigate their main performance criteria (in terms of modelling, dark current, light response, high-speed measurements). The implementation of a device architecture that relies on structures of different physical dimensions has the purpose of maximising the physical benefits of lower dimensional systems. The advantages of electron transport in a reduced dimensional system make these devices good candidates for integrated optoelectronic applications. The performance of this type of device was simulated using an ISE-TCAD simulator. Physical models used include Shockley-Reed-Hall recombination, Auger recombination, field-dependent mobility, thermionic effects, heterointerfaces and surface density of state-effects, considering also the specific quantized nature of the two-dimensional electron gas. We compared the simulated characteristics of AlGaAs/GaAs-based devices with measurements and obtained a good match between our simulation results and measurement data. The results show that the chosen physical model applied using the 2D device simulation is viable for the study and development of device performances. We also took into account photoresponse measurements of AlGaAs and InGaAs materials based devices, in order to evaluate the behavior of devices under light. High speed time response measurements are given in the last part of this paper that indicate higher peak transient response is achieved in the presence of higher 2DEG density, without degradation of temporal behavior. Microwave measurements taken in the frequency domain conclude the picture of characterizations, allowing us to extract the elements of the equivalent circuit.