AND, OR, NOT Logical Functions in a SiC Tandem Device

In this paper we demonstrate the basic AND, OR and NOT logical functions based on SiC technology. The device consists of a p-i’(a-SiC:H)-n/p-i(a-Si:H)-n heterostructure with low conductivity doped layers. Experimental optoelectronic characterization of the fabricated device is presented and shows the feasibility of tailoring channel bandwidth and wavelength by optical bias through illumination in the back and front sides. Results show that, front background enhances the light-to-dark sensitivity of the long and medium wavelength range and strongly quenches the others. Back violet background has the opposite behavior; it enhances the magnitude in short wavelength range and reduces it in the long ones. This nonlinearity provides the possibility for selective removal or addition of wavelengths. Each digital signal is composed by two wavelengths, one from the long and the other from the short range. One digital signal is the Red-Blue pair and the other the Green-Violet pair. Two digital light signals Manchester coded at 6000 Baud are applied do the front side of the device while violet light steadily shines either on the back or front side. Each signal pair will be presented first, independently, allowing the NOT logical function to be identified. The violet background biasing either in front or at the back of the device will allow for a non inverted or inverted signal. The interaction of two digital signals, (Red-Blue and Green-Violet pairs) will consequently be shown and the logical AND, OR operations identified by selecting the violet biasing illumination at either the back or front side of the device. The XOR logical function can also be identified along with the other logical functions. Experimental results are shown and explained with the two digital signal pairs.