Photoelectric Infrared CASCADE BASED nanoheterostructures InAs / GaAsN on a substrate of gallium arsenide

摘要

The proposed utility model relates to a semiconductor nanoheterostructures photovoltaic cells based on compounds of elements of the III and V of the periodic table, such as InAs, GaAs, GaN, GaP, InP and solid solutions of these compounds are used for the manufacture of solar cells, i.e. converting light energy from the sun into electrical energy, including multijunction (multistage).; Object of the present utility model, to provide an efficient photoelectric infrared cascade original design based nanoheterostructures InAs / GaAsN on a substrate of gallium arsenide, operating at wavelengths up to 1200 nm at room temperature (300 K). Using this stage as part of two-stage (the first stage on the basis of GaAs, a second stage on the basis of InAs / GaAsN) and three-stage (the first stage on the basis of InGaP, a second stage on the basis of GaAs, a third stage on the basis of InAs / GaAsN) solar cells allows to extend the range of the converted solar radiation in longer wavelengths in the solar spectrum up to wavelengths up to 1200 nm, and thereby, to increase their efficiency. Using this stage as part of a four (first stage on the basis of InGaP, a second stage on the basis of GaAs, a third stage on the basis of InAs / GaAsN fourth stage based on Ge) solar cells produced on Ge substrates, increases the efficiency of conversion of solar radiation in the spectral range 870 -1200 nm, to increase the open circuit voltage of the solar cell and thereby increase its efficiency.; Technical result, allowing to perform the task, is to use layers of the compounds and solid solutions which do not contain antimony, in particular nanoheterostructures InAs / GaAsN lowest energy optical transitions of 1.00 eV, i.e., 0.4 eV less than the lowest energy optical transitions in gallium arsenide. Moreover, the average lattice parameter used nanoheterostructures InAs / GaAsN practically coincides with the GaAs lattice parameter, and forming a gallium arsenide nanoheterostructures surface does not lead to crystal defects such as misfit dislocations.; Technical result is achieved due to the fact that the active region of the photoelectric infrared cascade based nanoheterostructures InAs / GaAsN consists of alternating ultrathin layers of narrow bandgap binary compound InAs and thicker layers of ternary solid GaAsN solution with a higher band gap where the distance between the ultrathin layers narrow bandgap binary InAs compound is selected so as to provide efficient overlap of the wave functions of carriers are localized in the region of these layers, in Meas area of ​​6-11 nm, and the thickness of ultrathin layers of narrow bandgap InAs binary compound of less than 0.5 nm, that is selected so as to prevent the formation of three-dimensional islands of indium arsenide on the epitaxial surface. The active area of ​​the proposed nanoheterostructures not doped with any impurity. Alloy p- and n-type doped only adjacent to the active region layers of gallium arsenide, as a result, are formed inside and nanogetsrostruktura pin electrical field separating the minority charge carriers in the active region. Asking nanogeterostruktur shows high quantum efficiency of conversion of optical radiation, an external quantum efficiency greater than 75% at zero reflection, which corresponds to an internal quantum efficiency of 90%, and also exhibits a high value of the open circuit voltage than 0.4 V. Moreover, when implementing a photoelectric infrared cascade are used only layers are binary compounds of InAs, GaAs, and the ternary solid solutions GaAsN, and which layers are either solid solutions containing indium and Zot at the same time, for example InGaAsN, absent, thereby increasing the life time of minority carriers but due to the reduced density of crystalline defects. Using similar nanoheterostructures InP / GaPAsN, with alternate ultrathin layers of InP and a wide-band layers GaPAsN, when forming a photoelectric cascade visible radiation range on substrates GaP and Si, with an average lattice parameter close to that parameter of said substrates also leads to the efficient conversion of solar radiation into electricity. The minimum energy optical transitions in superlattices changed by changing the period of the superlattice and elemental composition forming superlattice layers GaAsN, which vary only by changing the gallium flux on enitaksialnuyu surface. Also, instead of gallium arsenide substrate, as an alternative, it may be used a germanium substrate.