Design and Analysis of Gallium Nitride-Based p-i-n Diode Structure for Betavoltaic Cell with Enhanced Output Power...

In this work, Gallium Nitride (GaN)-based p-i-n diodes were designed using a computer aided design (TCAD) simulator for realizing a betavoltaic (BV) cell with a high output power density (P_out). The short-circuit current density (J_SC) and open-circuit voltage (V_OC) of the 17 keV electron-beam (e-beam)-irradiated diode were evaluated with the variations of design parameters, such as the height and doping concentration of the intrinsic GaN region (H_i-GaN and D_i-GaN), which influenced the depletion width in the i-GaN region. A high H_i-GaN and a low D_i-GaN improved the P_out because of the enhancement of absorption and conversion efficiency. The device with the H_i-GaN of 700 nm and D_i-GaN of 1 × 10¹⁶ cm^-3 exhibited the highest P_out. In addition, the effects of native defects in the GaN material on the performances were investigated. While the reverse current characteristics were mainly unaffected by donor-like trap states like N vacancies, the Ga vacancies-induced acceptor-like traps significantly decreased the J_SC and V_OC due to an increase in recombination rate. As a result, the device with a high acceptor-like trap density dramatically degenerated the P_out. Therefore, growth of the high quality i-GaN with low acceptor-like traps is important for an enhanced P_out in BV cell.