Journal of Computational Electronics

, Volume 15, Issue 1, pp 172–180 | Cite as

Characterization of AlGaN/GaN and AlGaN/AlN/GaN HEMTs in terms of mobility and subthreshold slope

  • Santashraya Prasad
  • Amit Krishna Dwivedi
  • Aminul Islam


This paper presents two structures of wide band gap high electron mobility transistor (HEMT). One structure is made-up of a stack of AlGaN layer over GaN layer. This structure is characterized by two-dimensional (2-D) electron gas layer formed at the interface of the AlGaN and GaN layers. The 2-D electron gas plays an important role in determining the carrier-mobility \((\upmu )\) and hence drain-to-source current \((I_\mathrm{DS})\) of HEMT. The other structure introduces an AlN spacer layer between the AlGaN and GaN layers to improve these characteristics. This paper compares the output characteristics curves \((I_\mathrm{DS}-V_\mathrm{DS})\) and transconductance characteristics curves \((I_\mathrm{DS}-V_\mathrm{GS})\) obtained from simulations performed using Silvaco \(\hbox {ATLAS}^\mathrm{TM}\). The modified structure with spacer layer shows improvements in carrier-mobility and hence drain-to-source current. This paper estimates and compares the subthreshold slope (SS) of the two devices. AlGaN/AlN/GaN HEMT offers an SS of 80 mV/decade whereas AlGaN/GaN HEMT offers an SS of 95 mV/decade. Thus, an improvement in SS of about 18.75 % is achieved in AlGaN/AlN/GaN HEMT compared to AlGaN/GaN HEMT. HEMT with spacer layer also offers 10\(\times \) improvement in \(I_{DS}\) as compared to HEMT without spacer layer. The proposed HEMTs achieve \(\approx \)3.19\(\times \) improvement in breakdown voltage, \(>\)1.3\(\times \) improvement in SS compared to HEMTs previously proposed in the literature.


AlGaN/GaN High-electron mobility transistor (HEMT) Spacer layer Mobility Subthreshold slope 


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Santashraya Prasad
    • 1
  • Amit Krishna Dwivedi
    • 1
  • Aminul Islam
    • 1
  1. 1.Birla Institute of Technology, MesraRanchiIndia

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