GaN-on-Si Double-Channel Bi-Directional Switch Free of Back-Gating Effects by Synchronized Photonic-Electronic Driving Scheme

A GaN-on-Si bi-directional switch (BDS) in the common-drain configuration is typically confronted with the back-gating effects that induce electron trapping in the buffer layer, resulting in severe dynamic on-resistance (RON) degradation and distortion in the chopping waveform that are currently addressed by active substrate control. In this work, a holistic approach is demonstrated to eliminate the back-gating effects in the GaN-on-Si BDS without using the active substrate control. Different from the conventional single-channel design, the proposed device features two closely coupled 2DEG channels in between there exists a hole-storage/spreading channel. With a synchronized photonic-electronic driving (SPED) scheme, in the on-state, electron-hole pairs (EHPs) are generated in the source-to-gate and gate-to-drain access regions by photons with an above-bandgap energy of ~3.65 eV from an off-chip photon source. The EHPs are separated by the vertical electric field, with the holes in the upper channel subsequently blocked by the thin inserted AlN barrier layer in the double-channel structure and spreading along the hole-storage/spreading channel to the gated region, providing effective shielding to the upper channel and inducing electrons in the lower channel to compensate for reduced 2DEG density. As a result, the double-channel BDS (DC-BDS) is free of back-gating effects.