Analysis of the AlGaN/GaN vertical bulk current on Si, sapphire, and free-standing GaN substrates

Abstract

The vertical bulk (drain-bulk) current (Idb) properties of analogous AlGaN/GaN hetero-structures molecular beam epitaxially grown on silicon, sapphire, and free-standing GaN (FS-GaN) have been evaluated in this paper. The experimental Idb (25–300 °C) have been well reproduced with physical models based on a combination of Poole-Frenkel (trap assisted) and hopping (resistive) conduction mechanisms. The thermal activation energies (Ea), the (soft or destructive) vertical breakdown voltage (VB), and the effect of inverting the drain-bulk polarity have also been comparatively investigated. GaN-on-FS-GaN appears to adhere to the resistive mechanism (Ea = 0.35 eV at T = 25–300 °C; VB = 840 V), GaN-on-sapphire follows the trap assisted mechanism (Ea = 2.5 eV at T > 265 °C; VB > 1100 V), and the GaN-on-Si is well reproduced with a combination of the two mechanisms (Ea = 0.35 eV at T > 150 °C; VB = 420 V). Finally, the relationship between the vertical bulk current and the lateral AlGaN/GaN transistor leakage current is explored.

Analysis of off-state leakage mechanisms in GaN-based MIS-HEMTs: Experimental data and numerical simulation

“…9). Similar results were reported by Srivastava et al in [21] and Perez-Tomas et al in [22], where the combined involvement of resistive and Poole-Frenkel transport mechanisms were proposed. Good agreement with vertical leakage current and Poole-Frenkel transport mechanisms has been recently reported by Uren et al in [23].…”

Trapping mechanisms in GaN‐based MIS‐HEMTs grown on silicon substrate

“…When the devices are submitted to high drain bias, electrons can be injected from the substrate to the buffer, through the highly defective AlN nucleation layer [12,13], eventually being trapped in the gate-drain access region. An evidence supporting this scenario is the correlation between capture-rate and substrate leakage-current [11].…”

Probing the effect of point defects on the leakage blocking capability of Al0.1Ga0.9N/Si structures using a monoenergetic positron beam

“…A similar observation for the leakage current at a high electric field has been also made by other groups. 39,40 As [C] increases, ln(J/E vf )ÀE 1=2 vf curves gradually became super-linear, suggesting a gradual deviation from a pure Poole-Frenkel conduction mechanism as increasing [C]. Figure 3 shows the S values of the Al 0.1 Ga 0.9 N layer with [C] ¼ 5 Â 10 17 cm À3 as a function of incident positron energy E. The mean implantation depth of positrons is shown on the upper horizontal axis.…”