Abstract
Using measured capacitance-voltage curves with different gate lengths and current–voltage characteristics at low drain-to-source voltage for the AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) of different drain-to-source distances, we found that the dominant scattering mechanism in AlGaN/AlN/GaN HFETs is determined by the ratio of gate length to drain-to-source distance. For devices with small ratio (here, less than 1/2), polarization Coulomb field scattering dominates electron mobility. However, for devices with large ratio (here, more than 1/2), longitudinal optical (LO) phonon scattering and interface roughness scattering are dominant. The reason is closely related to polarization Coulomb field scattering.
Highlights
Owing to potential applications in high power and high frequency electronic devices associated with outstanding material properties, AlGaN/GaN heterostructure field effect transistors (HFETs) have attracted extensive research to improve the device performance [1-3]
According to our former report, it is found that the ratio of gate length to drain-tosource distance has an important influence on electron mobility and determines the dominant scattering mechanism in the AlGaN/AlN/GaN HFETs with the drain-tosource distance of 100 μm [6]
The 2DEG electron mobility of the rectangular AlGaN/AlN/GaN HFETs with drain-to-source of 100 μm in [6] was shown in Figure 4a, and from the smallest to the largest in Schottky contact sizes, they are marked as 100-a, 100-b, 100-c, and 100-d
Summary
Owing to potential applications in high power and high frequency electronic devices associated with outstanding material properties, AlGaN/GaN heterostructure field effect transistors (HFETs) have attracted extensive research to improve the device performance [1-3]. The strained AlGaN/AlN/GaN heterostructure with a thin AlN interlayer has been the popular material structure for AlGaN/GaN HFETs due to the improved transport properties of two-dimensional electron gas (2DEG) and electron mobility [4,5]. According to our former report, it is found that the ratio of gate length to drain-tosource distance has an important influence on electron mobility and determines the dominant scattering mechanism in the AlGaN/AlN/GaN HFETs with the drain-tosource distance of 100 μm [6]. The above influence on the electron mobility in AlGaN/AlN/GaN HFETs with different drain-to-source distances has not been investigated.
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