J. Semicond. > 2015, Volume 36 > Issue 10 > 104002
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SEMICONDUCTOR DEVICES

Broadband terahertz radiation from a biased two-dimensional electron gas in an AlGaN/GaN heterostructure

Zhongxin Zheng1, 2, Jiandong Sun1, Yu Zhou1, Zhipeng Zhang1 and Hua Qin1,

+ Author Affiliations

 Corresponding author: Hua Qin, hqin2007@sinano.ac.cn

DOI: 10.1088/1674-4926/36/10/104002

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Abstract: The broadband terahertz emission from drifting two-dimensional electron gas (2DEG) in an Al-GaN/GaN heterostructure at 6 K is reported.The devices are designed as THz plasmon emitters according to the Smith-Purcell effect and the 'shallow water' plasma instability mechanism in 2DEG.Plasmon excitation is excluded since no signature of electron-density dependent plasmon mode is observed.Instead, the observed THz emission is found to come from the heated lattice and/or the hot electrons.Simulated emission spectra of hot electrons taking into account the THz absorption in air and Fabry-Pérot interference agree well with the experiment.It is confirmed that a blackbody-like THz emission will inevitably be encountered in similar devices driven by a strong in-plane electric field.A conclusion is drawn that a more elaborate device design is required to achieve efficient plasmon excitation and THz emission.

Key words: two-dimensional electron gas, hot electron, blackbody radiation, plasmon, Fabry-Pérot cavity



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Fig. 1.  (a) Device A: the grating-coupled 2DEG device. (b) Device B: the triple-gated 2DEG device. (c) Schematic of the measurement setup. (d) Transmission coefficient of the THz low-pass filter (LPF) installed in the silicon bolometer.

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Fig. 2.  THz emission spectra at different gate voltages. (a) Grating-coupled 2DEG device (Device A),the curves are offset by 0.5 for clarity. (b) Triple-gated 2DEG device (Device B),the curves are offset by 3 for clarity. The source-drain bias is modulated at 7 Hz.

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Fig. 3.  THz emission spectra at different drain-source biases. (a) Grating-coupled 2DEG device (Device A),the curves are offset by 0.6 for clarity. (b) Triple-gated 2DEG device (Device B),the curves are offset by 0.3 for clarity. The source-drain bias is modulated at 7~Hz.

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Fig. 4.  (a) Electric power (squares) and emission power (circles) as a function of the electric field for device B. (b) Frequency response characteristics measured at $E=$ 2.63,6.3,10 kV/cm. $P_1$ is the frequency characteristic curve of the bolometer. $P_5$ is the frequency characteristic curve for lattice radiation.

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Fig. 5.  (a) Measured and simulated emission spectra from hot electrons driven by an electric field of $E =$ 6.25 kV/cm. The transmission coefficient of the sapphire substrate is shown with an arbitrary unit. (b) Calculated transmission coefficient of the air column with a humidity of 3{\%} using program am.

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Table 1.   Gate parameters of devices A and B.

Device A Device B
Grating gate period Grating gate Source-drain distance Gate length Source-drain distance
#1 #2 #3 8 $\mu $m
200 nm 100 nm 8 $\mu $m 50 nm 100 nm 400 nm
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    Received: 08 April 2015 Revised: Online: Published: 01 October 2015

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      Article Navigation >  Journal of Semiconductors  > 2015  >  36(10): 104002
      Zhongxin Zheng, Jiandong Sun, Yu Zhou, Zhipeng Zhang, Hua Qin. Broadband terahertz radiation from a biased two-dimensional electron gas in an AlGaN/GaN heterostructure[J]. Journal of Semiconductors, 2015, 36(10): 104002. doi: 10.1088/1674-4926/36/10/104002 ****Z X Zheng, Jiandong Sun and O N Sun, Y Zhou, Z P Zhang, H Qin. Broadband terahertz radiation from a biased two-dimensional electron gas in an AlGaN/GaN heterostructure[J]. J. Semicond., 2015, 36(10): 104002. doi: 10.1088/1674-4926/36/10/104002.
      Citation:
      Zhongxin Zheng, Jiandong Sun, Yu Zhou, Zhipeng Zhang, Hua Qin. Broadband terahertz radiation from a biased two-dimensional electron gas in an AlGaN/GaN heterostructure[J]. Journal of Semiconductors, 2015, 36(10): 104002. doi: 10.1088/1674-4926/36/10/104002 ****
      Z X Zheng, Jiandong Sun and O N Sun, Y Zhou, Z P Zhang, H Qin. Broadband terahertz radiation from a biased two-dimensional electron gas in an AlGaN/GaN heterostructure[J]. J. Semicond., 2015, 36(10): 104002. doi: 10.1088/1674-4926/36/10/104002.
      shu

      Broadband terahertz radiation from a biased two-dimensional electron gas in an AlGaN/GaN heterostructure

      DOI: 10.1088/1674-4926/36/10/104002
      • 1.

        Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China

      • 2.

        University of Chinese Academy of Sciences, Beijing 100049, China

      Funds:

      Project supported by the National Basic Research Program of China (No.G2009CB929303), the National Natural Science Foundation of China (No.61271157), the China Postdoctoral Science Foundation (No.2014M551678), and the Jiangsu Planned Projects for Postdoctoral Research Funds (No.1301054B).

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      • Corresponding author: hqin2007@sinano.ac.cn
      • Received Date: 2015-04-08
      • Accepted Date: 2015-05-26
      • Published Date: 2015-01-25

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