We fabricate and characterize a radio-frequency semiconductor point-contact (rf-PC) electrometer analogous to radio-frequency single-electron transistors (rf-SETs) [see Schoelkopf et ah, Science 280, 1238 (1998)]. The point contact is formed by surface Schottky gates in a two-dimensional electron gas in an AlGaAs/GaAs heterostructure. In the present setup, the PC is operating as a simple voltage-controlled resistor rather than a quantum point contact and demonstrates a charge sensitivity of about 2 x 10~(-1)e/(Hz)～(1/2) at a bandwidth of 30 kHz without the use of a cryogenic rf preamplifier. Since the impedance of a typical point-contact device is much lower than the impedance of the typical SET, a semiconductor-based rf-PC, equipped with practical cryogenic rf preamplifiers, could realize an ultrafast and ultrasensitive electrometer.
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机译：我们制造和表征类似于射频单电子晶体管（rf-SET）的射频半导体点接触（rf-PC）静电计[参见Schoelkopf等，科学280，1238（1998）]。点接触是由AlGaAs / GaAs异质结构中二维电子气中的表面肖特基栅极形成的。在当前设置中，PC作为简单的压控电阻器而不是量子点触点工作，并且在1a时表现出约2 x 10〜（-1）e /（Hz）〜（1/2）的电荷灵敏度。无需使用低温射频前置放大器即可获得30 kHz的带宽。由于典型的点接触设备的阻抗远低于典型的SET的阻抗，因此配备有实用的低温rf前置放大器的基于半导体的rf-PC可以实现超快和超灵敏的静电计。
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Laboratory for Molecular-Scale Engineering, Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706;
