Recessed p-buffer layer SiC MESFET: A novel device for improving DC and RF characteristics

Improved multi-recessed 4H–SiC MESFETs with double-recessed p-buffer layer

“…Since the I dsat is in direct proportion to the channel doping and dimensions (N Â a), a large product of the channel doping or thickness is required to allow for high drain current [6,7]. However, a higher channel doping will increase gate-source capacitance (C gs ) and a thicker channel layer will lead to lower DC transconductance (g m ), which reduces the cut-off frequency (f T ) and the maximum oscillation frequency (f max ) [8,9]. Therefore, to reach the superior characteristics of the device, it is necessary to find a solution to the trade-off between RF characteristics and output power.…”

A novel 4H-SiC MESFET with ultrahigh upper gate

“…Many magnificent structures and new techniques based on the double-recessed (DR) structure have been reported [5], such as recessed source/drain drift region [6], multi-recessed source/drain drift region [7] and partly undoped space region [8]. The most important desire for 4H-SiC MESFET is to improve the maximum output power density (P max ) and RF characteristics [9][10][11][12][13]. However, the structures mentioned above achieve smaller capacitance but do not implement a larger current.…”

RF characteristics for 4H-SiC MESFET with a clival gate

“…However, this will result in poor breakdown characteristics. And especially, the short-channel effect will be increased owing to the increased thickness of the channel [5].To overcome these problems, many novel device structures have been proposed and studied rencently, such as double-recessed MESFET (DR-MESFET) [6] and multiple-recessed MESFET (MR-MESFET) structures [7].…”