Under the condition that the gate region two-dimensional electron gas (2DEG) was depleted, the open region electron mobility could be modulated by PCF scattering, to enable the modulation of I DS by V GS. The open-gate device had two working modes with different modulation abilities. In this paper, a novel AlGaN/GaN HFET which had an open gate structure and a new working mechanism was designed. Therefore, it should be entirely possible to design a new device structure using the mechanism of PCF scattering to achieve large-scale modulation of V th in AlGaN/GaN HFETs. To a certain extent, V th can reflect the voltage range in which the gate-source voltage ( V GS) can effectively modulate the drain-source current ( I DS), and PCF scattering is related to both V GS and I DS. It has an important influence on the gate region electron mobility, gate-source resistance, extrinsic transconductance, linearity and other characteristics of the devices 13, 14, 15, 16, 17. It is extremely difficult to change the V th of the device across a large range by simply adjusting the device structure.Īdditionally, polarization Coulomb field (PCF) scattering is an important scattering mechanism in AlGaN/GaN HFETs. It is usually necessary to change the epitaxial structure of the material or introduce new process steps, such as changing the thickness, doping concentration or Al composition of the barrier layer, plasma treatment of the material surface, growing an insulating layer with a certain thickness above the barrier layer, etc 7, 8, 9, 10, 11, 12. However, the common methods to change the V th of AlGaN/GaN HFETs are relatively complex. Whether for switching devices or RF power devices, the threshold voltage ( V th) is a very important parameter. The AlGaN/GaN heterostructure field-effect transistor (HFET), a type of wide-bandgap semiconductor electronic device, has the advantages of high breakdown voltage and high electron mobility, which has led to it being widely used in high frequency and high power applications 1, 2, 3, 4, 5, 6. When used as class-A voltage amplifiers, open-gate devices can achieve effective voltage amplification with very low power consumption. Also, the gate-source voltage modulated the open channel current by changing the channel electron mobility through polarization Coulomb field scattering. Corresponding theoretical analysis and calculations showed that its saturation mechanism was related to a virtual gate formed by electron injection onto the surface. When the gate-source voltage V GS ≤ − 4.5 V, only the open region was conductive, and a new working mechanism modulated the channel current. The open-gate device had two working modes with different transconductance. Through measurements, it was found that by changing the width of the opening, the threshold voltage of the device could be easily modulated across a larger range. Sample transistors of different structures and sizes were constructed. In this study, a novel AlGaN/GaN heterostructure field-effect transistor based on open-gate technology was fabricated.
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