Comparing Electrical Performance of Lateral GaN Schottky Barrier Diode with A-Plane ($11\bar2 0$) and M-Plane ($1\bar1 00$) Nonpolar Sidewall Contact

Regarding the structural innovation of GaN Schottky barrier diodes (SBDs), advanced performance has been attained by lateral GaN SBDs with partial or complete AlGaN barrier layer recesses at anode areas and gated Ohmic metal with double anode structures. In this letter, lateral SBD with a- and m-plane-oriented sidewall contacts were fabricated and characterized. The lateral SBD depended strongly on the nonpolar sidewall-metal plane orientation. The a-plane- oriented SBD devices demonstrated lower turn-on voltage, lower specific on-resistances (R
on,sp
), lower sub-threshold slope, and higher current density, and similar on-off ration compared to m-plane SBD sidewall devices. These results indicate that orienting lateral SBD toward the a-plane would allow for better on-state characteristics. The different GaN oriented sidewalls have a similar surface roughness of 0.35nm, confirmed by atomic force microscopy (AFM) measurement. The ideality factor and potential height of the lateral SBDs have extracted from the relationship of lnI-V plots. Regardless of the crystal orientation, the ideal factors of GaN SBDs fall between 1.6 and 1.8, and the Φ
b
is 0.65 and 0.69 eV for a-plane and m-plane devices, respectively, It could be speculated that the difference in polarization charges and/or surface oxides of the various crystal planes is what causes the variation in Schottky barrier height.