A trajectory model of incident electrons in semiconductor materials is built using Monte Carlo method

and based on this model

simulation can be carried out to achieve penetration depth and energy distribution of incident electrons in semiconductors.GaN PN junction betavoltaic microbatteries using radioisotopes Ni—63 as sources are studied to obtain the penetration path and energy distribution of incident electrons into GaN.The area where the beta energy is concentrated in GaN can be shown by analyzing simulation result

and the collection efficiency of beta energy can be highly increased if the PN junction depth of the GaN microbattery is set near the depth where the beta energy is concentrated.Experimentally

GaN betavoltaic microbatteries using Ni—63 as source

with depth of junction is 1 000

450 nm separately

are fabricated and tested

and the result shows that the electrical output performance of the microbattery is greatly improved when the microbattery has its junction depth optimized by Monte Carlo method.The energy conversion efficiency of the developed GaN microbattery is tested as 1.47 % and output power is in the scale of microwatt.The result can provide effective reference for design and fabrication of GaN beta-voltaic microbattery.