N-shaped negative differential resistance in a transistor structure with a resistive gate

Voltage-controlled negative differential resistance (NDR) characteristics in a N-AlGaAs/p⁺-GaAs/n-GaAs transistor structure are proposed and demonstrated. The gate, made using self-aligned p-type diffusion, is placed in the n-GaAs collector layer instead of the p⁺-GaAs base layer, resulting in a so-called resistive gate. For a fixed gate voltage, the device current is modulated by the applied anode voltage. Under appropriate gate voltage with respect to the anode, the device shows good voltage-controllable NDR characteristics, including large peak-to-valley current ratios (PTV´s) and a voltage extension in the N-shaped curve which is equivalent to the common-emitter breakdown voltage in a transistor. A numerical model based on the transistor model for the carrier transport in this device, taking account of the influence of the applied anode voltage on the gate, is proposed. The experimental results show large room temperature PTV´s (e.g., 140 at a gate bias of 1.5 V) and large voltage extension in N-shaped curves (about 9 V). Reasonable agreement between theoretical and experimental results is observed