The impact of doping on the efficiency of GaAs –diode with active graded GaInAs side border

Abstract

Background. The development of modern communication, security, and medical systems requires compact terahertz radiation sources that can operate under normal conditions. One of the most promising devices is solid-state electronics, namely, Gunn diodes. Gunn diodes are quite miniature devices capable of generating microwave current oscillations under normal conditions, but to generate in the sub-terahertz and terahertz range, they need to be modified to eliminate physical limitations that prevent generation in these ranges.

Purpose of Work. The aim of this work is to study the effect of the dopant concentration on the static and dynamic characteristics of a planar Gunn diode with a graded gap active side boundary.

Techniques and Methodology. To obtain the characteristics of the diode, the charge transfer processes in it are numerically modeled using the ensemble Monte Carlo method, taking into account all relevant scattering mechanisms and the process of shock ionization. The paper calculates the current density dependences at different values of the DC voltage across the diode, and determines the efficiency and AC power optimized by the operating voltage across the diode when the diode is in the generation mode. All calculations are carried out for different concentrations of the donor impurity in the diode channel and in the active side boundary at the resonator frequencies of 200 GHz and 250 GHz.

Results: The existence of optimal concentrations and the ratio between the concentrations in the diode channel and the side boundary are shown. The maximum value of efficiency corresponds to a concentration in the channel of about 10¹⁷ cm^-3 and the concentration of the donor doping in the active side boundary of 2·10¹⁶ cm^-3 at frequency 250 GHz are demonstrated.

Conclusions: Optimal doping concentration for Gunn diode of 1,28 µm with a graded gap active side boundary is above 10¹⁷ cm^-3 in diode channel, and at about 2·10¹⁶ cm^-3 in ASB. It is possible to give optimal generation condition at maximal frequency of diode.