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采用非晶态硅作为双极型微波功率晶体管的发射极材料,利用这种硅层的垂直电阻的镇流作用,能够消除发射极边缘的注入电流集边现象。与通常晶体管相比,FFJ的有效发射极面积对基极面积之比值提高2～3倍,输出功率-阻抗乘积提高5～10倍。 由于FFJ的发射极-基极结电容仅仅取决于它的发射极掺杂情况,因此,可以同时得到较小的基极电阻r_b和较高的发射极截止频率f_(TE)。f_(max)的数值可以比通常的晶体管高3～5倍。
Amorphous silicon is used as the emitter material of bipolar microwave power transistors. By utilizing the ballasting effect of the vertical resistance of this silicon layer, it is possible to eliminate the injection current edge phenomenon at the emitter edge. Compared with usual transistors, FFJ effective emitter area to base area ratio increased by 2 to 3 times, the output power - impedance product increased by 5 to 10 times. Since the emitter-base junction capacitance of the FFJ depends only on its emitter doping, both the smaller base resistance r_b and the higher emitter cutoff frequency f_ (TE) can be obtained at the same time. The f_ (max) value can be 3 to 5 times higher than the usual transistor.