Theoretical investigation of incomplete ionization of dopants in uniform and ion-implanted 4H-SiC MESFETs

The effects of incomplete ionization of nitrogen in 4H-SiC have been investigated. Poisson's equation is numerically analysed by considering the effects of Poole--Frenkel, and the effects of the potential on N^+_\rm d (the concentration of ionized donors) and n (the concentration of electrons). The pinch-off voltages of the uniform and the ion-implanted channels of 4H-SiC metal-semiconductor field-effect transistors (MESFETs) and the capacitance of the gate are given at different temperatures. Both the Poole--Frenkel effect and the potential have influence on the pinch-off voltage V_\rm p of 4H-SiC MESFETs. Although the C-V characteristics of the ion-implanted and the uniform channel of 4H-SiC MESFETs have a clear distinction, the effects of incomplete ionization on the C-V characteristics are not significant.