Experimentally Validated Physical Modelling of Asymmetric Spacer Layer Tunnel Diodes for THz Applications

In this work physical models of GaAs/AlAs and InGaAs/AlAs Asymmetric Spacer Layer Tunnel Diodes (ASPATs) with thin AlAs barriers were created using Silvaco ATLAS software. DC and RF characteristics of these ASPAT designs were obtained using the ATLAS semiconductor-insulator-semiconductor model. The simulated results were validated against measured results of fabricated ASPATs, grown using molecular beam epitaxy (MBE) with the same epitaxial designs. The models showed good scaling with device mesa area and good matching to both the DC and RF characteristics of the fabricated devices. Once experimentally validated models of the ASPAT diodes were produced, simulations were performed to investigate new metamorphic ASPAT devices in which InGaAs/AlAs devices are grown on GaAs substrates. These devices are the first demonstration of In_0.53Ga_0.47As/AlAs ASPATs grown on a GaAs platform. This has the potential to reduce cost and is a step forward for the manufacturability of low cost mmwave/THz detector devices. The simulations were compared with fabricated metamorphic ASPATs to better understand these new devices.