| AVS 65th International Symposium & Exhibition | |
| Electronic Materials and Photonics Division | Wednesday Sessions |
| Session EM+2D+SS-WeA |
| Session: | Wide and Ultra-Wide Bandgap Materials for Electronic Devices: Growth, Modeling and Properties |
| Presenter: | Dong Ji, UC Davis |
| Authors: | S.C. Chowdhury, UC Davis D. Ji, UC Davis |
| Correspondent: | Click to Email |
Vertical GaN devices are ideal for high power applications owing to their wide bandgap-originated material properties, similar to SiC. What makes GaN vertical devices more attractive than SiC, is the capability to offer bulk regions with electron mobility over 1200cm2/V·sec. Due to higher carrier mobility made possible by superior growth techniques, the figure of merit offered by GaN diodes or FETs is higher compared to SiC counterparts. From TCAD drift diffusion simulation we have shown the advantage of GaN devices become rapidly significant over SiC diodes at higher voltages. In our experimental studies we have successfully demonstrated transistors blocking over 1.4kV.
In this presentation, we will go over various types of vertical devices for power conversion that we are pursuing in our group and go over the achievements and challenges in each.
CAVETs were the first vertical devices[1] that demonstrated the potential of GaN in these technology. CAVETs are realized with Mg-ion implanted [2] current blocking layers (CBLs) with regrown channel. Alternatively they can have Mg-doped CBLs with a regrown channel layer on a trench. In our trench CAVETs we have successfully blocked up to 880V with an Ron less than 2.7milli-ohm cm2.
To date, most successful results in GaN vertical devices have come out of MOSFETs, which traditionally rely on inversion channels. MOSFETs with an un-doped GaN interlayer as a channel and in-situ MOCVD oxide, called OG-FET have demonstrated superior performance with low specific on-state resistance (Ron) Over 1.4kV blocking with an Ron less than 2.2milli-ohm cm2 was recently demonstrated by our group where the role of channel mobility got highlighted[3].
One of common issue in all these devices is the realization of a robust buried p-n junction, which we will also go over along with other challenges faced by each of these device types and discuss paths to overcome those.
1. S. Chowdhury, M. H. Wong, B. L. Swenson, and U. K. Mishra, IEEE Electron Device Letters 33, 41 (2012).
2. S. Mandal, A. Agarwal, E. Ahmadi, K. M. Bhat, D. Ji, M. A. Laurent, S. Keller, and S. Chowdhury, IEEE Electron Device Letters, 38, 7 (2017)
3.D. Ji, C. Gupta, S. H. Chan, A. Agarwal, W. Li, S. Keller, U. K. Mishra, and S. Chowdhury, International Electron Devices Meeting, IEDM, 2017