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RESEARCH PAPER

Characteristics of High-Al-Composed Quantum Structure Under Strain Effects Salih Saygı1 Received: 15 September 2020 / Accepted: 30 October 2020 Ó Shiraz University 2020

Abstract A heterojunction field effect transistor has been studied by a model run self-consistently from the solution of the Schro¨dinger equation coupled with Poisson equation. The properties of the device drain current, the band structure of device, and the charge distribution have been obtained because of material composition. The efforts have shown that unique reason of having the high carrier concentration in heterostructures is to manage with the piezoelectric and spontaneous polarization. Simulation by means of polarization-related quantities in nitride-based heterostructure systems reveals that the device characterizations of nitride alloys are a linear function of alloy composition. Our simulation results are comparable to other theoretical calculations. Keywords FET devices  Modeling  Strain effects  Alloy composition

1 Introduction GaN-based compounds show a low density, a good resistance to corrosion, high electrical and thermal conductivity, and a high specific strength after the construction of heterojunctions. Many research groups with the motivation of implying the channel with aluminum gallium nitride AlGaN barrier layer have attempted to grow low defect films on substrates through major advantages of AlxGa1-xN ternary compounds with high aluminum Al content. With the high breakdown voltage and good thermal conductivity, as well as with the low defect levels, the high Al composition devices are expected to show better abilities than that of grown with lower composition devices (Raman et al. 2008; Nanjo et al. 2008). However, the achievement of high Al content layers is not been effortless due to dislocations and creaks. In addition, the stress between the layers limits the channel layer thickness. For thicker and low-defect AlGaN layer using pulsed molecular chemical vapor deposition MOCVD procedure has developed by applying various growth factors which result in reasonable & Salih Saygı [email protected] 1

Department of Physics, Science Faculty, Gaziosmanpasa University, 60250 Tokat, Turkey

reduction for dislocations (Khan et al. 1990; Hu et al. 2018). Highlighting the processes, even with unintentionally doped heterosystem barriers, the high sheet carrier concentration can be kept if only a typical III-V material, gallium nitride GaN, is used, where a specific direction plane growth of material is more obvious. Thus far, it is known that the carrier density and mobility depend drastically on the layer interface charge that is caused by the spontaneous and piezoelectric polarization in the materials (Oberhuber et al. 1998). The efforts have shown that unique reason of having the high carrier concentration in heterojunctions is to manage with the piezoelectric and spontaneous polarization (Bykhovski et al. 1996; Ambacher et al. 1999). It must be sensibly consid