Over 50 mA Current in Interdigitated Diamond Field Effect Transistor

This letter presents the bulk diamond field-effect transistor (FET) with the highest current value reported at this moment on 3.5 $\times $ 3.5 mm2 Ib diamond substrate. The goal was to drastically increase the current of this type of device by increasing the total gate width thanks to an interdigitated architecture and homogeneous growth properties. The device develops a total gate width of 14.7 mm, with 24 paralleled fingers and a current higher than 50 mA at V $_{\text {DS}} = -15$ V and V $_{\text {GS}} =0$ V, at 450 K and under illumination. Its specific ON-resistance and threshold voltage are respectively 608 m $\Omega $ .cm2, 50 V. Resistivity of 3.6 m $\Omega $ .cm for a heavily boron-doped (p++)-diamond layer and $1.52\Omega \cdot $ cm for a $2.10^{{17}}$ cm−3 p-doped diamond layer were extracted at 450 K. This study indicates that it is possible to drastically improve the ON-state of FETs by using an interdigitated architecture, while using homogeneous large size diamond layers grown by CVD.