Photodetectors are fabricated on GaAs substrate using dilute nitride technology for high speed-high-sensitivity operation for telecom and datacom applications for the wavelength ranges covering O-band (Original band: 1260 nm to 1360) to C-band (conventional band: 1530-1565 nm).

A semiconductor device includes a silicon substrate and a detection element and p-type and n-type MOS transistors, which are arranged on the silicon substrate, wherein the detection element includes a semiconductor layer, electrodes, and a Schottkey barrier disposed therebetween, the semiconductor layer is arranged just above a layer having the same composition and height as those of an impurity diffusion layer in the source or drain of the p-type or n-type MOS transistor, a region, in the silicon substrate, having the same composition and height as those of a channel region, in the silicon substrate, just below a gate oxide film of the p-type MOS transistor or the n-type MOS transistor, or a region, in the silicon substrate, having the same composition and height as those of a region just below a field oxide film disposed between the p-type and the n-type MOS transistor.

A MESFET transistor on a horizontal substrate surface with at least one wiring layer on the substrate surface. The transistor comprises source, drain and gate electrodes which are at least partly covered by a semiconducting channel layer. The source, drain and gate electrodes optionally comprise interface contact materials for changing the junction type between each electrode and the channel. The interface between the source electrode and the channel is an ohmic junction, the interface between the drain electrode and the channel is an ohmic junction, and the interface between the gate electrode and the channel is a Schottky junction. The substrate is a CMOS substrate.

Techniques to use energy band gap engineering (or band offset engineering) to produce a photodetector semiconductor assembly that can be tuned to absorb light in one or more wavelengths. For example, the assembly can be tuned to receive infrared (IR) and/or ultraviolet (UV) light. The photodetector assembly can operate as a photodiode, a phototransistor, or can include both a photodiode and a phototransistor.

A UV sensor includes a GaN stack including a low-resistance GaN layer formed over a nucleation layer, and a high-resistance GaN layer formed over the low-resistance GaN layer, wherein a 2DEG conductive channel exists at the upper surface of the high-resistance GaN layer. An AlGaN layer is formed over the upper surface of the high-resistance GaN layer. A source contact and a drain contact extend through the AlGaN layer and contact the upper surface of the high-resistance GaN layer (and are thereby electrically coupled to the 2DEG channel). A drain depletion region extends entirely from the upper surface of the high-resistance GaN layer to the low-resistance GaN layer under the drain contact. An electrical current between the source and drain contacts is a function of UV light received by the GaN stack. An electrode is connected to the low-resistance GaN layer to allow for electrical refresh of the UV sensor.

A UV sensor includes a GaN stack including a low-resistance GaN layer formed over a nucleation layer, and a high-resistance GaN layer formed over the low-resistance GaN layer, wherein a 2DEG conductive channel exists at the upper surface of the high-resistance GaN layer. An AlGaN layer is formed over the upper surface of the high-resistance GaN layer. A source contact and a drain contact extend through the AlGaN layer and contact the upper surface of the high-resistance GaN layer (and are thereby electrically coupled to the 2DEG channel). A drain depletion region extends entirely from the upper surface of the high-resistance GaN layer to the low-resistance GaN layer under the drain contact. An electrical current between the source and drain contacts is a function of UV light received by the GaN stack. An electrode is connected to the low-resistance GaN layer to allow for electrical refresh of the UV sensor.

Example photoconductive devices and example methods for using photoconductive devices are described. An example method may include providing a photoconductive device having a metal-semiconductor-metal structure. The method may also include controlling, based on a first input state, illumination of the photoconductive device by a first optical beam during a time period, and controlling, based on a second input state, illumination of the photoconductive device by a second optical beam during the time period. Further, the method may include detecting an amount of current produced by the photoconductive device during the time period, and based on the detected amount of current, providing an output indicative of the first input state and the second input state. The example devices can be used individually as discrete components or in integrated circuits for memory or logic applications.

Techniques to use energy band gap engineering (or band offset engineering) to produce a photodetector semiconductor assembly that can be tuned to absorb light in one or more wavelengths. For example, the assembly can be tuned to receive infrared (IR) and/or ultraviolet (UV) light. The photodetector assembly can operate as a photodiode, a phototransistor, or can include both a photodiode and a phototransistor.

An MSM ultraviolet ray receiving element has a low dark state current value and a good photosensitivity. The MSM ultraviolet ray receiving element has a first nitride semiconductor layer on a substrate, a second nitride semiconductor layer on the first nitride semiconductor layer, and first and second electrodes on the second nitride semiconductor layer. The first nitride semiconductor layer contains Al.sub.XGa.sub.(1-X)N (0.4X0.90). The second nitride semiconductor layer contains Al.sub.YGa.sub.(1-Y)N with a film thickness t (nm) satisfying 5t25. The first electrode and the second electrode contain a material containing at least three elements of Ti, Al, Au, Ni, V, Mo, Hf, Ta, W, Nb, Zn, Ag, Cr, and Zr. Al composition ratios X and Y and a film thickness t satisfy 0.009t+X+0.220.03Y0.009t+X+0.22+0.03.

A MESFET transistor on a horizontal substrate surface with at least one wiring layer on the substrate surface. The transistor comprises source, drain and gate electrodes which are at least partly covered by a semiconducting channel layer. The source, drain and gate electrodes optionally comprise interface contact materials for changing the junction type between each electrode and the channel. The interface between the source electrode and the channel is an ohmic junction, the interface between the drain electrode and the channel is an ohmic junction, and the interface between the gate electrode and the channel is a Schottky junction. The substrate is a CMOS substrate.