Abstract: The invention provides a semiconductor light emitting device and the method of making it. The semiconductor light emitting device, according to the invention, includes an undoped InxGAyAl2N film, as an Ohmic layer, formed between a top-most semiconductor material layer and a transparent conductive oxide layer. Since the undoped film as a tunneling layer is very thin (?20 angstroms), the electric field across the tunneling layer, under forward bias, will make electron tunneling from valence band to conduction band, and return to the transparent conductive layer, A reasonably low and stable forward voltage of the semiconductor light emitting device according to the invention can be achieved.

Abstract: The present invention provides a motor control system and method thereof. The motor control system comprises a motor controller and a compensation device. The motor controller is used for generating a motor control output according to a reference signal and a first signal. The compensation device is used for generating a compensated motor control output according to the motor control output and a second signal. Moreover, the compensation device utilizes the compensated motor control output to reduce the steady-state phase error between the first signal and the reference signal.