The bipolar mode field effect transistor (BMFET) as an optically controlled switch: numerical and experimental results

The use of the optically controlled devices is very attractive in power applications where serious problems can occur when high voltage control is required. In this context, optical switching of electronic devices is instrumental for the electrical insulation between control and power circuits. On this line of argument we have demonstrated the possibility of optically switching a BMFET (bipolar mode field effect transistor) by means of a low power laser diode. After carrying out a detailed theoretical and numerical analysis of the optically controlled BMFET, we have performed different experimental measurements. In particular, by using a BMFET that can block 1300 V and conducts peak drain currents up to 10 A, we have been able to switch an electrical power up to 1 kW by a laser diode of 25 mW operating at 830 nm. This corresponds to a power gain G/sub P/ (defined as the ratio between the switched electrical power and the optical power) equal to about to 40000. Both experimental and numerical results have shown that, for optical switching application, the BMFET works much better than an electrically equivalent bipolar junction transistor (BJT).