Isoelectronic co-doping
AssigneeMidwest Research Institute
InventorAngelo Mascarenhas
Life of this patent
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Abstract
Isoelectronic co-doping of semiconductor compounds and alloys with deep acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, N and Bi, to customize solar cells, thermal voltaic cells, light emitting diodes, photodetectors, and lasers on GaP, InP, GaAs, Ge, and Si substrates. Isoelectronically co-doped Group II-VI compounds and alloys are also included.
Claims135
A method of modifying a semiconductor compound or alloy comprising host atoms in a host crystal lattice to have a lower effective bandgap than the semiconductor compound or alloy has prior to modification, comprising:
- isoelectronically co-doping the semiconductor compound or alloy with a first isoelectronic dopant comprising atoms that form isoelectronic electron traps in the host crystal lattice that behave as deep acceptors and with a second isoelectronic dopant comprising atoms that form isoelectronic hole traps in the host crystal lattice that behave as deep donors.
11 The method of claim 4, wherein the Group III and V host atoms comprise Ga and P.
The method of claim 11, wherein the first isoelectronic dopant comprises N and the second isoelectronic dopant comprises Bi.
A method of modifying a Group III-V semiconductor compound or alloy to have a lower effective bandgap than the Group III-V semiconductor compound or alloy has prior to modification, comprising:
- isoelectronically co-doping the Group III-V compound or alloy with more than 1 at. % of an isoelectronic deep acceptor element and more than 1 at. % of an isoelectronic deep donor element.
A method of modifying a semiconductor compound or alloy comprising host crystal atoms in a host crystal lattice to have a lower effective bandgap than the semiconductor or alloy has prior to modification, comprising:
- isoelectronically co-doping the semiconductor compound or alloy with a first isoelectronic atomic species and a second isoelectronic atomic species,
- wherein said first isoelectronic atomic species is sufficiently different in electronegativity, size, and pseudo potential difference from host crystal atoms that are substrituted by the first isoelectronic atomic species to generate an isoelectronic trap whose impurity potential is sufficiently deep and of a very short range to behave as acceptors, and
- wherein said second isoelectronic atomic species is sufficiently different in electronegativity, size, and pseudo potential difference from host crystal atoms that are substituted by the second isoelectronic atomic species to generate an isoelectronic trap whose impurity potential is sufficiently deep and of a very short range to behave as donors.
A semiconductor material for use as an active cell in a semiconductor device, comprising:
- a semiconductor compound or alloy comprising host atoms in a host crystal lattice that is isoelectronically co-doped with a first isoelectronic dopant comprising atoms that form isoelectronic traps in the host crystal lattice that behave as deep acceptors, and with a second isoelectronic dopant comprising atoms that form isoelectronic traps in the host crystal lattice that behave as deep donors.
A monolithic, quadruple junction solar cell, comprising:
- a first cell comprising Ge with a bandgap of about 0.67 eV;
- a second cell comprising GaAs that is isoelectronically co-doped with a deep acceptor element and a deep donor element to have an effective bandgap of about 1.05 eV on the first cell;
- a third cell comprising GaAs with a bandgap of about 1.42 eV on the second cell;
- and
- a fourth cell comprising InGaP with a bandgap of about 1.90 eV on the third cell.
A two-junction tandem solar cell, comprising:
- a bottom cell comprising a Si substrate with a bandgap of about 1.1 eV and that has a charge-doped junction;
- and
- a top cell on the bottom cell, said top cell comprising GaP that is isoelectronically co-doped with a deep acceptor element and a deep donor element to have an effective bandgap of about 1.75 eV and that has a charge-doped-junction.
A three-junction tandem solar cell, comprising:
- a first cell comprising a Si substrate with a bandgap of about 1.1 eV and that has a charge-doped junction;
- a second cell on said first cell, said second cell comprising GaP that is isoelectronically co-doped with a deep acceptor element and a deep donor element to have an effective bandgap of about 1.55 eV and that has a charge-doped p-n junction;
- and
- a third cell on said second cell, said third cell comprising GaP that is isoelectronically co-doped with a deep acceptor element and a deep donor element to have an effective bandgap of about 2.05 eV and that has a charge-doped p-n junction.
A method of fabricating GaP semiconductor material on a Si crystal lattice, comprising:
- depositing a thin fihn of GaP at a temperature of at least about 700° C. on the Si crystal lattice to achieve two-dimensional growth of polar GaP on non-polar Si;
- and
- isoelectronically co-doping the thin filn of GaP with a deep acceptor element and a deep donor element in a proportion that reduces compressive misfit strain of the GaP on the Si crystal lattice to a residual misfit strain of the isoelectronically co-doped GaP on the Si crystal lattice that is of lesser magnitude than the compressive misfit strain of the GaP on the Si crystal lattice.
A method of modifying indirect bandgap GaP to act like a direct bandgap semiconductor material, comprising:
- isoelectronically co-doping GaP with N and Bi to form a GaP:N:Bi crystal lattice such that content of the N in the GaP:N:Bi crystal lattice is more than 3 at. % and content of the Bi in the GaP:N:Bi is more than 2 at. %.
A light-emitting diode, comprising:
- an active layer of Group III-V semiconductor compound or alloy that is isoelectronically co-doped with a deep acceptor element and a deep donor element, said active layer being sandwiched between:
- (i) a first barrier layer of the Group III-V semiconductor compound or alloy charged-doped to either n-type or p-type;
- and (ii) a second barrier layer of the Group III-V semiconductor alloy charged-doped to either n-type or p-type, whichever is opposite the charge-doped first barrier layer.
A thermal voltaic cell, comprising:
- an InP substrate with a bandgap of about 1.45 eV;
- and
- a semiconductor cell deposited on the inP substrate, said semiconductor cell comprising InGaAs semiconductor alloy that is isoelectronically co-doped with N deep acceptor atoms and Bi deep donor atoms to provide an InGaAs:N:Bi crystal lattice.
A GaAs-based laser device, comprising:
- an active layer comprising GaAs that is isoelectronically co-doped with an isoelectronic atomic species that creates a deep acceptor in the GaAs and with an isoelectronic atomic species that creates a deep donor;
- and
- a bottom cladding layer and a top cladding layer sandwiching said active layer.
A laser diode, comprising:
- an active region comprising a set of isoelectronically co-doped Group III-V semiconductor compound or alloy MQW layers separated by barrier layers of Group III-V semiconductor compound or alloy, said active region being sandwiched between a bottom SCH layer of Group III-V semiconductor compound or alloy and a top SCH layer of Group III-V semiconductor compound or alloy;
- a bottom cladding layer of group III-V semiconductor compound or alloy underlaying the bottom SCH layer;
- and
- a top cladding layer of Group III-V semiconductor compound or alloy overlaying the top SCH layer.
A photodiode, comprising:
- an active junction of isoelectronically co-doped Group III-V semiconductor compound or alloy fabricated on a substrate of Group III-V semiconductor compound or alloy.
Dependencies are inferred from the claim text.