Split-gate InGaAs quantum wire device operated at 80 K

Reports the electrical characteristics of InGaAs quantum wire devices based on deep mesa-etched structures with split gate. Quantized conductance and quantized currents have been observed at 80 K. The heterostructure of the devices consists of a 2000-AA GaAs layer grown on undoped GaAs substrates, a 1.0- mu m AlSb buffer layer, a 2000-AA (Al/sub 0.5/Ga/sub 0.5/)Sb buffer layer, a 70-AA AlSb layer, a 150-AA InAs layer, a 150-AA (Al/sub 0.5/Ga/sub 0.5/)Sb layer, and a 100-AA GaSb layer. Clear quantized conductance steps of three to five fold multiples of (2e/sup 2//h) were observed at 80 K with an InAs wire width of 3500 AA. Clear conductance steps were observed at even higher temperatures up to 120 K. However, the conductance values at steps at those higher temperatures above 100 K do not agree with multiples of (2e/sup 2//h). This is probably due to the parasitic MESFET which turns on very weakly at high temperatures.