Though the complementary power field effect transistors (FETs), e.g., metal–oxide–semiconductor-FETs (MOSFETs) based on wide bandgap materials, enable low switching losses and on-resistance, p-channel FETs are not feasible in any wide bandgap material other than diamond. In this paper, we propose the first work to investigate the impact of fixed positive surface charge density on achieving normally-off and controlling threshold voltage operation obtained on p-channel two-dimensional hole gas (2DHG) hydrogen-terminated (C-H) diamond FET using nitrogen doping in the diamond substrate. In general, a p-channel diamond MOSFET demonstrates the normally-on operation, but the normally-off operation is also a critical requirement of the feasible electronic power devices in terms of safety operation. The characteristics of the C–H diamond MOSFET have been analyzed with the two demonstrated charge sheet models using the two-dimensional Silvaco Atlas TCAD. It shows that the fixed-Fermi level in the bulk diamond is 1.7 eV (donor level) from the conduction band minimum. However, the upward band bending has been obtained at Al2O3/SiO2/C-H diamond interface indicating the presence of inversion layer without gate voltage. The fixed negative charge model exhibits a strong inversion layer for normally-on FET operation, while the fixed positive charge model shows a weak inversion for normally-off operation. The maximum current density of a fixed positive interface charge model of the Al2O3/C-H diamond device is − 290 mA/mm, which corresponds to that of expermental result of Al2O3/SiO2/C-H diamond − 305 mA/mm at a gate-source voltage of − 40 V. Also, the threshold voltage Vth is relatively high at Vth = − 3.5 V, i.e., the positive charge model can reproduce the normally-off operation. Moreover, we also demonstrate that the Vth and transconductance gm correspond to those of the experimental work.
Though the complementary power field effect transistore (FETs), e.g., metal-oxide-semiconductor-FETs (MOSFETs) based on wide badgap materials, enable low switching losses and on-resistance, p-channel FETs are not feasible in any wide bandgap material other than diamond. In this paper, we propose the first work to investigate the impact of fixed positive surface charge density on achieving normally-off and control threshold voltage operation obtained on p-channel two-dimensional hole gas (2DHG) hydrogen-terminated diamond (C-H) FET using deep nitrogen doping in the diamond substrate. In general, a p-channel diamond C-H MOSFET demonstrates normally-on operation, but the normally-off operation is also a critical requierment of the feasible electronic power devices in terms of safety operation. The evaluation results of the characteristic of the C-H MOSFET capacitor with the two demonstrated charge sheet models using the two-dimensional Silvaco Atlas TCAD show that the fixed-Fermi level is a function of capacitance-voltage with an activation energy of 1.7 eV (donor level) at the H-diamond surface close to minimum conduction band. The maximum current density with a positive surface charge model and a nitrogen-doped layer of the Al2O3/H-diamond device is -52 mA/mm at a gate-source voltage of -42 V. Also, the gate threshold voltage is relatively high at Vth= -3 V, i.e., the positive surface charge model can achieve the normally-off operation. Moreover, we demonstrate that the obtained results correspond to the experimental work with the SiO2 layer located below the gate in C-H diamond/Al2O3 surface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.