Self-protected GaN power devices with reverse drain blocking and forward current limiting capabilities

Self-protected GaN power devices were realized using AlGaN/GaN-on-Si platform, where two built-in intelligent functions were demonstrated for “Smart Discrete” applications. First, an AlGaN/GaN normally-off high electron mobility transistor (HEMT) with reverse drain blocking capability was realized, featuring a Schottky contact controlled drain barrier. Compared to the Schottky drain structures, the new design exhibits only a 0.55 V onset voltage in the forward biased “ON” state, while effectively blocks the reverse current conduction. The device fabrication is also free of extra photomask and process steps. Second, an AlGaN/GaN lateral field-effect rectifier (L-FER) with intrinsic “ON” state current limiting capability was fabricated, featuring a depletion-mode (D-mode) Schottky controlled depletion-mode channel extension (length of L_D) beyond the ohmic contact at the cathode electrode, where the on-state current of the new rectifiers are self-limited at 4.59 kA/cm² (L_D = 1.3 μm) and 3.56 kA/cm² (L_D = 1.9 μm) at room temperature. The current limiting level shows a negative temperature coefficient (TC) that is desirable for thermal stability.