Shot noise of a high-speed resonance-tunneling diode based on the GaAs/AlAs heterosystem

Abstract

A method for the measurement of the shot noise of semiconductor diodes at low temperatures and frequencies of no less than 100 MHz is proposed. The technique is based on the Y-factor method that is modified for the measurement in which the device under study is not matched with the measurement circuit. The shot noise of high-speed resonance-tunneling diodes (RTDs) based on the GaAs/AlAs heterosystem is analyzed. It is demonstrated that an increase in the bias voltage leads to an increase in the Fano factor from about 0.5 at low bias to values of greater than unity in the range of the negative differential conductance of the RTD. When the bias voltage further increases, the Fano factor decreases and becomes close to 0.5. At all of the temperatures and bias voltages, a reliable decrease in the Fano factor to a level of less than 0.5 is not observed. We assume the sequential rather than coherent electron transport for the RTD based on the GaAs/AlAs heterosystem.