Study Of InGaN/GaN Homotype Heterojunction IMPATT Diodes For Millimeter Wave Application

Millimeter wave technology is expected to play a key role in the next generation of mobile communication technology,imaging,monitoring and other information technology fields.As a millimeter wave solid-state source,Impact-Ionization-Avalanche-Transit-Time（IMPATT）diode has obvious advantages in efficiency and power characteristics.The third generation semiconductor material（SiC,GaN）has many advantages,such as high critical electric field,high carrier mobility and high thermal conductivity.It has become an important candidate material for semiconductor devices such as IMPATT diodes.However,because p-typeGaN materials are difficult to produce high concentrations of ionizing holes,the performance of devices will be limited,and due to the existence of process bottlenecks,most of the research ofGaN based IMPATT comes from theoretical analysis and device simulation.The practical application and industrialization of IMPATT devices are seriously hindered.The third generation semiconductor materials and their heterostructure IMPATT devices have great application potential.In this work,a novel n-In_xGa_1-xN/n-GaN homotype heterostructure IMPATT is proposed and simulated.In this paper,the DC and AC output characteristics and noise characteristics of the novel structure device with different In composition are studied in detail.It is found that the n-In_xGa_1-xN/n-GaN structure IMPATT diode can replace the traditionalGaN based p-n junction IMPATT diode,and has the same or even better output characteristics as the traditional structure,so as to avoid the problem of using p-type material inGaN based IMPATT diode.It provides a new idea and reference for the design of IMPATT devices based on wide band gap semiconductor materials,especiallyGaN materials.The specific research contents and results are as follows:（1）The device simulation and device-circuit mixmode simulation are carried out on the Silvaco-ATLAS platform,in which the free-running oscillation circuit and voltage controlled oscillation circuit are used for the simulation of AC performance,the negative resistance of IMPATT diode is judged through Fourier analysis,and the performance indexes such as power and efficiency of IMPATT output are further calculated;（2）The static performance simulation results of the device with different In compisition are obtained,including the electric field distribution,impact ionization rate distribution and carrier distribution under thermal equilibrium and reverse breakdown.The results show that the new device has better static parameters under different parameters.Through the conclusions of this chapter,it can be predicted that it can produce oscillation waveform output like traditional IMPATT diode,and has higher potential in AC performance;（3）The device-circuit mixmode simulation obtains the AC performance simulation results of the device,including phase difference between AC current and voltage,efficiency,power,negative resistance and other parameters.The AC power and DC-AC conversion efficiency of homotype heterostructure IMPATT increase with the increase of In composition,can be improved by up to 0.33 W/cm² and 3.52%.When the In composition is greater than 0.4,the power and efficiency of the novel structure are better than the traditional p-n junction IMPATT device.At the same time,homotype heterostructure IMPATT has a larger frequency bandwidth,it can maintain a larger bias current density than p-n junction IMPATT;（4）At the same time,the simulation results of the noise performance of the device with different In composition are obtained.The AC performance and noise performance of homotype heterostructure IMPATT do not significantly depend on the thickness of InGaN layer,but for p-n IMPATT,it’s output performance will decrease with the increase of the thickness of p-type region.The unit bandwidth mean square noise voltage of the novel device can be reduced 4.89×10^-17 V²·s,and noise measurement can be reduced by 6.45 d B to 14.10d B.