In this paper, some interesting features of a microelectronic gas discharge device with GaP semiconductor are reported. The device is a complicated plasma system with a metal anode and a GaP cathode. A discharge occurs in the micro-scaled gap, when a voltage larger than the breakdown value is applied between these electrodes. Since large region of applied voltages are scanned in the microelectronic gas discharge device, both Townsend and glow regimes are clearly observed and a complete electrical and optical responses of the device has been clarified. Following the increase of U gradually, different light emission intensities occur as a result of discharge current I. An IR light source is also used in order to test the IR excitation of the microstructure. Although it has been believed that the GaP is sensitive to UV and visible regions, it has been proven for the first time that the IR sensitivity of GaP can be enhanced by using microelectronic gas discharge device, when an appropriate parameter set is applied. Moreover, a negative differential resistance regime, which is important for the high frequency microwave applications, has been observed at moderate voltages. In addition to the negative differential resistance regime, certain hysteresis behaviour is also observed in the sweep up/down cases of U.