SiC MESFET由于其高击穿电压和低输出电容,适合用于设计E类功率放大器。设计了一种结构简单的微带线拓扑E类负载网络,可以匹配至标准电阻,且抑制高至5阶的谐波。用ADS软件进行电路仿真,在2.14 GHz频率点下,峰值功率附加效率(PAE)为70.5%,漏极效率可达80%,功率增益约为10 dB。
The intrinsic defects in epitaxial semi-insulating 4H-SiC prepared by low pressure chemical vapor deposition (LPCVD) are studied by electron spin resonance (ESR) with different illumination times.The results show that the intrinsic defects in as-grown 4H-SiC consist of carbon vacancy (V C ) and complex-compounds-related V C.There are two other apexes presented in the ESR spectra after illumination by Xe light,which are likely to be V Si and V C C Si.Illumination time changes the relative density of intrinsic defects in 4H-SiC;the relative density of intrinsic defects reaches a maximum when the illumination time is 2.5 min,and the ratio of V C to complex compounds is minimized simultaneously.It can be deduced that some V Si may be transformed to the complex-compounds-related V C because of the illumination.
This paper reports that Ni and Ti/4H-SiC Schottky barrier diodes(SBDs) were fabricated and irradiated with 1 MeV electrons up to a dose of 3.43×10^(14) e/cm^2.After radiation,the Schottky barrier heightφb of the Ni/4H-SiC SBD increased from 1.20 eV to 1.21 eV,but decreased from 0.95 eV to 0.94 eV for the Ti/4H-SiC SBD.The degradation ofφB could be explained by interface states of changed Schottky contacts.The on-state resistance R_S of both diodes increased with the dose,which can be ascribed to the radiation defects.The reverse current of the Ni/4H-SiC SBD slightly increased,but for the Ti/4H-SiC SBD it basically remained the same.At room temperature,φB of the diodes recovered completely after one week,and the R_S partly recovered.
