Homemade-HEMT-based transimpedance amplifier for high-resolution shot-noise measurements

Abstract

We report a cryogenic transimpedance amplifier (TA) suitable for cross-correlation current-noise measurements. The TA comprises homemade high-electron-mobility transistors with high transconductance and low noise characteristics, fabricated in an AlGaAs/GaAs heterostructure. The low input-referred noise and wide frequency band of the TA lead to a high resolution in current-noise measurements. The TA’s low input impedance suppresses unwanted crosstalk between two distinct currents from a sample, justifying the advantage of the TA for cross-correlation measurements. We demonstrate the high resolution of a TA-based experimental setup by measuring the shot noise generated at a quantum point contact in a quantum Hall system.

Fast time-domain current measurement for quantum dot charge sensing using a homemade cryogenic transimpedance amplifier

“…In this characterization, the TIA cooled down to 4.2 K converts a sinusoidal alternating current (AC) of Iin = 10 nArms to an output voltage Vout = ZtransIin with its specific transimpedance Ztrans. 30% reduction compared with the previous report [19]. The noise floor between 100 kHz and 1 MHz, decreasing almost linearly with increasing RFB, is close to the thermal noise 4kBT/RFB of the feedback resistance, indicating that the thermal noise dominates the noise floor over the HEMT's input voltage and current noise.…”

“…The characteristic frequency fC, above which the noise amplitude increases with frequency, due to the increased noise gain, is about one megahertz. The fC value is almost doubled compared with the previous TIA [19], indicating a lower-noise performance at high frequencies. Figure 2(d) summarizes f−3dB and minimal Sinput of our TIAs.…”

“…When RFB = 400 kΩ is used, the average input-referred noise Sinput−av in the measurement bandwidth of Δf = 900 kHz (from 0.1 to 1 MHz) is about 1.17×10 −27 A 2 /Hz. With the data integration time of τint = 10 s, we expect the resolution of an autocorrelation current-noise measurement to reach Sinput−av/√(Δf  τint) ≈ 3.9× 10 −31 A 2 /Hz, which is better than that achieved in the previous TIA-based setup [19] and that in a conventional setup using a cryogenic voltage amplifier and an RLC resonator [16,24].…”

“…Here, H1-H5 labels the five homemade HEMT chips, whose channel width W = 3 mm and gate length Lg = 4 μm [16]. While the circuit design follows that of the TIA developed for shot-noise measurement on a mesoscopic sample [17][18][19],…”

“…The data of our previous TIA are shown in black [19]. (d)Summary of minimum Sinput (vertical axis) and f−3dB (horizontal axis) at 4.2 K (red triangles), plotted with those of our previous TIA (black circle[19]). The dashed line indicates the expected performance of our TIA at 1 K.…”