| 초록 |
We investigated the effects of in situ silicon carbon nitride (SiCN) cap layer of AlGaN/GaN high-electron mobility transistors (HEMTs) on DC, capacitance-voltage (C-V), and low-frequency noise (LFN). The proposed device with SiCN cap layer exhibited the enhanced drain current, reduced gate leakage current, low interface trap density (Dit), and high on/off ratio thanks to the passivation effect compared to the device without SiCN cap layer. Both devices clearly showed 1/f noise behavior with carrier number fluctuations (CNF) plus correlated mobility fluctuations (CMF), regardless of the existence of SiCN cap layer. In comparison with DC and C-V characteristics of both devices, the increased noise level with the relative high trap density (Nit) for the proposed device (Nit = 3.5 × 1020 cm-3·eV-1) was observed compared to the device without SiCN cap layer (Nit = 9.2 × 1018 cm-3·eV-1) due to the multiple trapping/detrapping into two gate insulators; (1) AlGaN barrier layer and (2) SiCN cap layer. On the other hand, the proposed device presented less CMF term and reduced access noise due to the effective surface passivation in source-drain access region. |
