Solar cells (SCs) based on III-V semiconductors are reviewed. Presented work emphases on the Solar Cells containing Quantum Dots (QDs) for next-generation photovoltaics. In this work the method of fabrication of InP QDs on III-V semiconductors is investigated. The original method of electrochemical deposition of metals: indium (In), gallium (Ga) and of alloys (InGa) on the surface of gallium phosphide (GaP), and mechanism of formation of InP QDs on GaP surface is presented. The possibilities of application of InP/GaP/Si structure as SC are discussed, and the challenges arising is also considered.
We present the results of experimental studies of physical properties of the detection process of GaAs Schottky diodes
for terahertz frequency radiation. The development of technology in the THz frequency band has a rapid progress
recently. Considered as an extension of the microwave and millimeter wave bands, the THz frequency offers greater
communication bandwidth than is available at microwave frequencies. The Schottky barrier contact has an important role
in the operation of many GaAs devices. GaAs Schottky diodes have been the primary nonlinear device used in
millimeter and sub millimeter wave detectors and receivers. GaAs Schottky diodes are especially interesting due to their
high mobility transport characteristics, which allows for a large reduction of the resistance-capacitance (RC) time
constant and thermal noise.
In This work are investigated the electrical and photoelectric properties of GaAs Schottky diodes. Samples were obtained
by deposition of different metals (Au, Ni, Pt, Pd, Fe, In, Ga, Al) on semiconductor. For fabrication metal-semiconductor
(MS) structures is used original method of metal electrodepositing. In this method electrochemical etching of
semiconductor surface occurs just before deposition of metal from the solution, which contains etching material and
metal ions together. For that, semiconductor surface cleaning processes and metal deposition carries out in the same
technological process. In the experiments as the electrolyte was used aqueous solution of chlorides. Metal deposition was
carried out at room temperature.
The effect of annealing structures on the electrical and photoelectric properties of metal-semiconductor contacts was investigated. Metal/semiconductor structures have been fabricated by method of electrochemically deposition of In on the electrochemically cleaned surface of the semiconductors A3B5 (GaP, GaAs). The dark capacitance and current -voltage characteristics and the hotoelectric spectra of zero bias for front-illuminated contact show near-ideal Schottky barrier diode properties for annealing temperature up to 250-3000C. Was found that the spectra of zero bias photocurrent of In/GaP beside the region photoconductivity resulting from band to band excitation, contains, also, separated of them the region photoconductivity in a long wavelength of spectra, which is related to the interaction between the metal and semiconductor. Samples used for the fabrication of In/GaP diodes were growing by Chochralski method especially un doped n-type GaP into (III) oriented wafers. The thickness and carrier concentration was 200-250 mimic and (2-4). 10 exp17 atom/cm3 respectively. At first ohmical contact to the one side of wafer was formed by alloying of indium at the temperature 5000C for GaAs and 600°C for GaP during 5 min in hydrogen. Then the sample with ohmic contact and wire for preceding the power was coaled with chemical stable polystyrene solution except the area where the metal will be deposited. The wafers were then ached chemically, rinsed in distilled water and were transferred immediately into electrolyte for deposition of In.
Samples used for the fabrication of M-S diodes were growing by Chochralski method especially undoped n-type GaP into (III) oriented wafers. The thickness and carrier concentration was 200-250 mimic and (2-4). 10 exp17 atom/cm3 respectively. At first ohmical contact to the one side of wafer was formed by alloying of indium at the
temperature 600°C during 5 min in hydrogen. Then the sample with ohmical contact and wire for preceding the power was covered with chemical stable polystyrene solution except the area where the metal will be deposited. The wafers were then ached chemically, rinsed in distilled water and were transferred immediately into electrolyte. Deposition of metal was done by the usual electrochemical method. Electrolyte was poured into quartz glass. The semiconductors wafer was used as the one electrode and as another electrode was used aluminum. For deposition Al the aqueous solution of chlorides have been used as an electrolyte, which consisted also <i>NaOCI</i>. At first, semiconductor’s wafer was used as the anode and cleaning of semiconductors surface was done. Then the potential was immediately changed in opposite direction and deposition of metal on freshly cleaned surface was done in the same solution in a united technological process. After the process of realization the samples were washed in distilled water. The polystyrene film was removed mechanically and boiling in acetone. Then samples were cut into pieces of area 1-3 mm, and were measured electric and photoelectric characteristics. The electrical and photoelectric characteristics have been studded and they were analyzed in the usual way to calculate the ideality factor (n) and barrier height (o). The values of coefficient n and SB height were 1.05-1.07 and 1.1 eV respectively.