Characteristic of RTD for Different Parameters and Material Properties

Simulation of larger device structure is difficult due to meshing problem and is too time consuming. So, a small structure is simulated as replica of a larger one to investigate the qualitative features. Higher figures of merit (PVR) may be conveniently realized for the GaInAs/A1InAs system. Constructional features for these diodes are the same as for the GaAs/GaAlAs systems. Only GaInAs replaces GaAs and AlInAs replaces GaAlAs. The improvement for this system is essentially due to a larger value of the barrier potential and lower value of the effective mass in the well.Further improvement in device characteristics may achieved by using AlAs barrier layers in place of A1InAs barriers. From the simulated result, it is found that PVR is very high than GaInAs/A1InAs based RTD. But NDR appears at higher voltages. To achieve PVR at lower voltage, barrier thickness must be increased or well thickness must be decreased. By introducing InAs layer as well material the higher voltage problem associated with AlAs barrier can be minimized. This increases the PVR and NDR occurs at lower voltages. But the dimension of InAs layer must be within a limit, otherwise PVR can¿t be achieved at desired.