Experimental and Theoretical Investigation of Collector Spacer and Doping Profile on Triple-Barrier Resonant Tunneling Diodes

Upcoming THz applications require compact, robust, and efficient sources with high output-power. Among electronic devices, resonant tunneling diodes are a promising candidate for THz operation. Triple-barrier resonant tunneling diodes provide a high degree of design and operation freedom. Zero-bias detection and THz emission are possible with the same device due to the asymmetric structure and IV curve. However, more investigations in the layer stack design are required. An investigation is presented into the effect of collector spacer thickness and doping profile in the subcollector contact region. The aim is to simultaneously optimize the RF output-power and cut-off frequency in triple-barrier structures. A series of devices with different collector spacers and two distinct doping profiles are fabricated. A trade-off between collector spacer thickness and doping profile for either higher output power or cut-off frequency is observed. In addition, the simulation results are presented from a nonequilibrium Green's function solver implemented in Python. Herein, a need for accurate determination of the extent of the nonequilibrium region to achieve simulation results matching the IV measurements is observed.