ACTIVATION CHARACTERISTICS OF A LONG-WAVELENGTH INFRARED HOT-ELECTRONTRANSISTOR

The origin of current reduction in an infrared hot-electron transistor is examined by studying the thermal activation energy of the emitter and the collector dark current as a function of emitter bias V(e). For the emitter, the activation energy E(ae) is found to be determined by the thermionic emission (TE) process at a small V(e). At higher V(e), E(ae) decreases linearly with V(e) due to the increase of the thermal ly assisted tunneling (TAT) current enhanced by dopant migration. For the collector, the activation energy E(ac) is significantly higher tha n E(ae) at low biases, indicating that the collector accepts higher en ergy electrons injected from the emitter. For the device under study, at V(e)=0.5 V, the value of E(ac) is the same as that of the emitter a t low biases. This result shows that, up to this bias, the collector d ark current consists of only the TE current but not the TAT current, t hus greatly improving the detector performance.