Monte Carlo simulation of real-space transfer transistors: device physics and scaling effects

Monte Carlo simulations of the real-space transfer transistor (RSTT) are carried out for various bias conditions. Detailed analysis of the RSTT, especially in the saturation regime, is performed. The mechanism responsible for the saturation of the source current is explained in terms of reverse real-space transfer. The operation of the RSTT is compared with that of the charge injection transistor and it is pointed out that the difference in geometry of these two devices leads to different physical operation. The effect of reducing the device dimensions on the RSTT performance is discussed. A reduction in the collector length is found to improve the transconductance. Transient analysis of the RSTT shows that the device with a smaller collector length would exhibit higher cutoff frequencies. A reduction in the width of the collector drift region is shown to result in an increased peak-to-valley ratio in the heater current which makes the drive more efficient for microwave generation