Abstract
The new optical gating technique uses a femtosecond optical laser pulses for the photoconductive detection of short pulses of terahertz (THz) radiation. This technique reproduces the shape of the THz pulse and after pulse plasmonic response of the two-dimensional electron gas in a short channel high electron mobility transistor (HEMT). The results are in excellent agreement with the electro-optic effect measurements and with the simulation results obtained in the frame of a two-dimensional hydrodynamic model. The femtosecond optical laser pulse time is delayed with respect to the THz pulse and generates a large concentration of the electron-hole pairs in the AlGaAs/InGaAs HEMT. This drastically increases the channel conductivity on the femtosecond scale and effectively shorts the device quenching the transistor response. The achieved time resolution is better than 250 femtoseconds and could be improved using shorter femtosecond laser pulses. The spatial resolution of this technique is on the order of tens of nanometers or even smaller. It could be applied for studying the electron transport in a variety of electronic devices ranging from silicon MOSFETs to heterostructure bipolar transistors.
Highlights
The emergence of high resolution video stimulated interest in future wireless communications operating at frequencies of 300 GHz and above 1,2,3,4, which, in turn, stimulated research on new terahertz detectors and sources 5,6,7,8, including plasmonic devices 9,10,11,12,13, operating in both collision dominated 14, and quasi ballistic regimes 15
We report on the new optical gating technique that was used for the direct photoconductive detection of short pulses of terahertz radiation with the resolution up to 250 femtoseconds
The characteristic High Electron Mobility Transistor (HEMT) response time depends on the duration of the THz pulse, THz, the plasma wave transit time, p, and the momentum relaxation time, m
Summary
The emergence of high resolution video stimulated interest in future wireless communications operating at frequencies of 300 GHz and above 1,2,3,4, which, in turn, stimulated research on new terahertz detectors and sources 5,6,7,8, including plasmonic devices 9,10,11,12,13, operating in both collision dominated 14, and quasi ballistic regimes 15. The measurement results confirm that the transistor plasmonic response is at the subpicosecond scale in a good agreement with the predictions of our hydrodynamic model.
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