Materials and processing issues in vertical GaN power electronics

Abstract

Silicon-based power devices are reaching their fundamental performance limit. The use of wide-bandgap semiconductors with superior material properties over silicon offers the potential for power electronic systems with much higher power densities and higher conversion efficiency. GaN, with a high critical electric field and carrier mobility, is considered one of the most promising candidates for future high-power, high frequency and high temperature applications. High voltage transistors and diodes based on both lateral and vertical structures are of great interest for future power electronics. Particularly, vertical GaN power devices have recently attracted increasing attention due to their many unique properties. This paper reviews recent progress and key remaining challenges towards the development of high-performance vertical GaN transistors and diodes with emphasis on the materials and processing issues related to each device architecture.

HCl Flow-Induced Phase Change of α-, β-, and ε-Ga2O3 Films Grown by MOCVD

“…Further studies regarding kinetic models may be required to unveil the whole mechanism of the crystallization process with HCl including: (1) fully understand the growth rate versus the HCl flow rates of Ga2O3 with the same phase. (2) Oversupply HCl gas into the chamber to check the phases and growth rate. (3) Replace HCl with other gas to conduct similar study etc.…”

Review of the Recent Progress on GaN-Based Vertical Power Schottky Barrier Diodes (SBDs)

“…The typical schematic structure of GaN SBD is shown in Figure 1a,b, including quasi-vertical and fully-vertical structure [16][17][18][19][20][21][22]. For the quasi-vertical GaN SBD, a mesa structure is processed and both Quasi-vertical SBDs have several drawbacks [20,22]: (1) nonuniform distribution of current, (2) the current crowding problems, (3) large total device area, and (4) the deep etched sidewall process. All these issues greatly promote the development of fully-vertical SBD, where the electrodes (anode and cathode) are located at two sides of the wafer separately, with current flowing from anode to cathode through the drift layer in a vertical direction, as shown in Figure 1b.…”

“…However, a large number of dislocations in the GaN drift layer can cause leakage current when device is reverse biased [40,41]. To study the substrates impact on the performance of GaN-based power device, Figure 2 summarizes the data from The GaN epitaxy layer grown on GaN substrate has lower dislocation densities than foreign substrates (e.g., Si, sapphire, or SiC), because of low lattice mismatch and low thermal expansion coefficient mismatch [20][21][22][23][24][25][26][27]. However, the dislocation density of GaN-on-GaN is limited by the defect density in the GaN substrate [28][29][30].…”

Power-dependent physical properties of $$\mathbf{GaN}$$ thin films deposited on sapphire substrates by RF magnetron sputtering

“…III-Nitride semiconductors (direct-wide band gap ∼1.95− 6.2 eV) play an important role in optoelectronic applications [1][2][3]. Recently, many distinguished scientists have explored such materials deeply for use in high technology [4][5][6][7][8][9][10][11][12].…”