An AlN/Ultrathin AlGaN/GaN HEMT Structure for Enhancement-Mode Operation Using Selective Etching

作者：Anderson Travis J^*; Tadjer Marko J; Mastro Michael A; Hite Jennifer K; Hobart Karl D; Eddy Charles R Jr; Kub Francis J

来源：IEEE Electron Device Letters, 2009, 30(12): 1251-1253.

DOI：10.1109/LED.2009.2033083

• GaN
• high-electron-mobility transistor (HEMT)
• normally off
• wet etch

A novel device structure incorporating an ultrathin AlGaN barrier layer capped by an AlN layer in the source-drain access regions has been implemented to reliably control threshold voltage in AlGaN/GaN high-electron-mobility transistors. A recessed-gate structure has been used to decrease 2-D electron gas (2DEG) density under the gate, thus controlling threshold voltage while maintaining low on-resistance and high current density. The structure presented in this letter implements an ultrathin AlGaN structure grown by metal-organic chemical vapor deposition capped with AlN to maintain a high 2DEG density in the access regions. A selective wet etch using heated photoresist developer is used to selectively etch the AlN layer in the gate region to the AlGaN barrier. We have demonstrated a repeatable threshold voltage of +0.21 V with 4-nm AlGaN barrier layer thickness.

• 出版日期2009-12