Abstract: A field-effect transistor includes a Ga2O3-based semiconductor layer, a source region and a drain region that are formed inside the Ga2O3-based semiconductor layer, a gate electrode that is formed, via a gate insulating film, on a channel region as the Ga2O3-based semiconductor layer between the source region and the drain region, a source electrode connected to the source region, and a drain electrode connected to the drain region. An interface charge including a negative charge is formed between the gate electrode and the channel region, and a gate threshold voltage is not less than 4.5V.

Abstract: There is provided a laser diode drive signal processor for driving a laser diode to be used to emit a laser beam for accessing an optical information recording medium with the laser beam. The processor has an alternating current side driving current supply circuit for supplying a first driving current according to a signal level of an alternating current component; a photo diode coupled to the laser diode for detecting a light amount of the laser beam; error signal generating circuit for generating an error signal based on the detected light amount of the laser beam and a reference signal; direct current side driving current supply circuit for supplying a second driving current according to a signal level of the error signal; and adding circuit for adding the first driving current from the alternating current side driving current supply circuit and the second driving current from the direct current side driving current supply circuit to generate a third driving current.