一种带有极化掺杂电流阻挡层的垂直AlGaN/GaN HFET

针对传统垂直GaN基异质结场效应晶体管中,由于GaN电流阻挡层内p型杂质激活率低而导致的漏电问题,提出了一种使用AlGaN极化掺杂电流阻挡层的垂直GaN基异质结场效应晶体管结构。在AlGaN极化掺杂电流阻挡层中,通过Al组分渐变而产生的极化电场来提升p型杂质激活率,能更加有效地抑制截止状态下通过极化掺杂电流阻挡层的泄漏电流,从而提升器件的耐压能力。此外,极化掺杂电流阻挡层内空穴浓度的增大会降低器件导通电阻,但由于极化掺杂电流阻挡层与n-GaN缓冲层之间形成的二维电子气会阻挡耗尽层向缓冲层内的扩展,极化掺杂电流阻挡层的使用对器件导通电阻几乎没有影响。

A Novel Vertical AlGaN/GaN HFET with Polarization-Doped Current Blocking Layer

A novel vertical GaN-based heterojunction field-effect transistor (VHFET) with polarization-doped current blocking layer (PD-CBL) was proposed. The p-type dopant activation efficiency in the AlGaN PD-CBL was enhanced significantly by graded Al composition. The leakage current through PD-CBL was effectively suppressed by the increased hole concentration and electron barrier height in the PD-CBL, which leaded to a drastically improvement of the breakdown voltage. Moreover, although the increased hole concentration in PD-CBL tended to increase the ON-state resistance, due to the suppression of the depletion region in the GaN buffer by the 2DEG formed at the PD-CBL/buffer interface, negligible negative impact on the on-state resistance was observed for the as-proposed devices.