GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT

Tansen Varghese

Patent

Atlas literature

Patent

US 8,753,918

GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT

Tansen Varghese, Arthur Cornfeld

Claims

Claims define the patent's legal scope. Independent claims stand alone; dependent claims (nested) narrow them. Click a claim to expand its dependents.

60 independent · 4 dependent

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  Dependent← claim 6, claim 60GaAsGePdInGa(Al)P top subcellInGaAs bottom subcellInGaAlAs graded interlayerinverted metamorphic multijunction solar cell
  The method as deﬁned in claim 60 [[73]], where in the upper ﬁrst solar subcell is composed of InGa(Al)P 75 The method as deﬁned in claim 60 [[73]], where in the middle second solar subcell is composed of an GaAs, Ga I nP, Ga InAs, GaAsSb, or Ga InAs N emitter region and a GaAs, Ga InAs, GaAsSb, or Ga InAs N base region 76 The method as deﬁned in claim 60 [[73]], where in the lower third solar subcell is composed of an InGaAs base and emitter layer, or a InGaAs base layer and a InGaP emitter layer 77 The method as deﬁned in claim 60 [[73]], where in the graded in terlayer is composed of InGaA 1As 78 The method as deﬁned in claim 60 [[73]], where in the graded in terlayer has a band gap of approximately 1 5 eV throughout its thickness 79 The method as deﬁned in claim 60 [[73]], where in the graded in terlayer is composed of any of the As, N, Sb based I II -V compound semiconductors subject to a constra in t of hav in g an in-plane lattice parameter greater or equal to that of the middle second solar subcell and less than or equal to that of the lower third solar subcell, and hav in g a band gap energy greater than that of the middle second solar subcell Amendment and Response Page 5 of 14 App li cation No 13/603,088 Conﬁrmation No 6649 Filed For GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT (as amended) 80 The method as deﬁned in claim 6 0_ [[73]], where in the graded in terlayer is composed of (In xGai_X)yAli_y As, with x and y selected such that the band gap of the transition mate ri al rema in s constant throughout its thickness 81 The method as deﬁned in claim 78, where in said graded in terlayer is composed of ni ne or more steps of layers of semiconductor material with monoto ni cally chang in g lattice constant and constant band gap 82 A method of form in g a multijunction solar cell compris in g a top subcell, at least one middle subcell, and a bottom subcell, the method compris in g form in g a semiconductor contact layer composed of GaAs over the top subcell, deposit in g a metal contact layer compris in a sequence of layers inc lud ing Pd/Ge/T i/Pd pallad um4ayef over the semiconductor contact layer us ing e-beam evaporation, and form in g an ohmic metal contact from the metal contact layer to the semiconductor contact layer hav in g a speciﬁc contact resistance of less than 2 x 1 0-4 ohms-cm2 83 The method as deﬁned in claim 82, where in the palladium layer has a thickness of 50 nm and the germa ni um layer has a thickness of 100 nm 84 The method as deﬁned in claim 82, where in the palladium layer is disposed adjacent to the semiconductor contact layer, and the germa ni um layer is disposed on top of the palladium layer 85 The method as deﬁned in claim 82, where in the metal contact layer is heated at 210 degrees C or less 86 The method as deﬁned in claim 85, where in the metal contact layer is heated for approximately 35 m in utes or less Amendment and Response Page 6 of 14 App li cation No 13/603,088 Conﬁrmation No 6649 Filed For GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT (as amended)
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IndependentGaAsGePdinverted metamorphic multijunction solar cell
A method of form in g a solar cell compris ing provid in g a semiconductor body inc lud in g at least one photoactive j unction, form in g a semiconductor contact layer composed of GaAs deposited over the semiconductor body, and deposit in g a metal contact layer inc lud in g a germa ni um layer and a palladium layer over the semiconductor contact layer, and sm ter mg the metal contact la yer so that the speciﬁc contact resistance is less than 5 x 10-4 ohms- cm21 where in the semiconductor body in cludes an upper ﬁrst solar subcell, a middle second solar subcell, a graded m terla y er, and a lower third solar subcell, where in the upper ﬁrst solar subcell has a ﬁrst band g a p, where in the middle second solar subcell has a second band g ap smaller than said ﬁrst band gap, where in the graded m terla yer dis posed over said middle second solar subcell is compositionally graded to lattice match the middle second solar subcell on one side and the lower third solar subcell on the other side, and where in the lower third solar subcell is disposed over said graded m terla y er and has a fourth band g a p smaller than said second band gap such that said lower third solar subcell is lattice mismatched with respect to said middle second solar subcell 61 The method as deﬁned in claim 60, where in the palladium layer has a thickness of 50 nm and the germa ni um layer has a thickness of 100 nm Amendment and Response Page 3 of 14 App li cation No 13/603,088 Conﬁrmation No 6649 Filed For GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT (as amended) 62 The method as deﬁned in claim 60, where in the palladium layer is disposed adjacent to the semiconductor contact layer, and a germa ni um layer is disposed on top of the palladium layer 63 The method as deﬁned in claim 60, where in the metal contact layer is sin tered at 210 degrees C or less 64 The method as deﬁned in claim 63, where in the metal contact layer is sin tered for approximately 35 m in utes or less 65 The method as deﬁned in claim 60, where in the metal contact layer is a sequence of layers inc lud in g Pd/Ge/T i/Pd
1. 67
  Dependent← claim 60, claim 63GaAsGePdPd/Ge/Ti/Pd/Ag/Au metal contact stackinverted metamorphic multijunction solar cell
  The method as deﬁned in claim 60, where in the speciﬁc contact resistance is less than 5 x 1 0- 6 ohms-cm2 68 The method as deﬁned in claim 60, where in the speciﬁc contact resistance is less than 1 x 1 0-4 ohms-cm2 69 The method as deﬁned in claim 60, where in the metal contact layer is composed of a Pd/Ge/T i/Pd/Ag/Au sequence of layers 70 The method as deﬁned in claim 60, where in the metal contact layer is deposited by e-beam evaporation 71 The method as deﬁned in claim 63, where in the s in ter in g is performed in ambient atmosphere on a hot plate Amendment and Response Page 4 of 14 App li cation No 13/603,088 Conﬁrmation No 6649 Filed For GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT (as amended) 72 The method as deﬁned in claim 60, where in the semiconductor body is a triple j unction solar cell composed of I II -V compound semiconductor material
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Dependent← claim 82GaAsGePdPd/Ge/Ti/Pd/Ag/Au metal contact stackinverted metamorphic multijunction solar cell
The method as deﬁned in claim 82, where in the metal contact layer comp ri ses a sequence of layers selected from of the group consist in g of Pd/Ge/Au, Pd/Ge/Ag, Pd/Ge/Pt/Au, Pd/Ge/Pt/Ag, Pd/Ge/Pt/Ag/Au, Au/Ge/Pd/Au, Pd/Ge/T i/Pd/Au, and Pd/Ge/T i/Pd/Ag/Au 89 The method as deﬁned in claim 82, where in the metal contact layer is sin tered for approximately 5 m in utes at 280 degrees C 90 The method as deﬁned in claim 82, where in the speciﬁc contact resistance between the metal contact layer and the semiconductor contact layer is less than 5 x 1 0- 6 ohms- 2 cm 91 The method as deﬁned in claim 82, where in the speciﬁc contact resistance is less than 1 x 1 0-4 ohms-cm2
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Dependent← claim 82, claim 85GaAsGePdInGa(Al)P top subcellInGaAs bottom subcellInGaAlAs graded interlayerinverted metamorphic multijunction solar cell
The method as deﬁned in claim 85, where in the heat in g is performed in ambient atmosphere on a hot plate 94 The method as deﬁned in claim 82, where in the multi j unction solar cell is a triple j unction solar cell composed of I II -V compound semiconductor mate ri al inc lud in g the top subcell, the at least one middle subcell, and the bottom subcell, where in the top subcell has a ﬁrst band gap, the at least one middle subcell has a second band gap smaller than said ﬁrst band gap, a graded in terlayer is disposed over said at least one middle subcell that is compositionally graded to lattice match the at least one middle subcell on one side and the bottom subcell on the other side, the bottom subcell disposed over said graded m terlayer has a fourth band gap smaller Amendment and Response Page 7 of 14 App li cation No 13/603,088 Conﬁrmation No 6649 Filed For GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT (as amended) than said second band gap such that said bottom subcell is lattice mismatched with respect to said at least one middle subcell 95 The method as deﬁned in claim 94, where in the upper subcell is composed of InGa(Al)P 96 The method as deﬁned in claim 94, where in the at least one middle subcell is composed of an GaAs, Ga I nP, Ga InAs, GaAsSb, or Ga InAs N emitter region and a GaAs, GaInAs, GaAsSb, or Ga InAs N base region 97 The method as deﬁned in claim 94, where in the lower subcell is composed of an InGaAs base and emitter layer, or a InGaAs base layer and a InGaP emitter layer 98 The method as deﬁned in claim 94, where in the graded in terlayer is composed of InGaA 1As 99 The method as deﬁned in claim 94, where in the graded m terlayer has a band gap of approximately 1 5 eV throughout its thickness 100 The method as deﬁned in claim 94, where in the graded in terlayer is composed of any of the As, N, Sb based I II -V compound semiconductors subject to a constra int of hav in g an m -plane lattice parameter greater or equal to that of the second solar subcell and less than or equal to that of the second solar subcell and less than or equal to that of the third solar subcell, and hav in g a band gap energy greater than that of the second solar subcell 101 The method as deﬁned in claim 94, where in the graded m terlayer is composed of (In xGai_X)yAli_y As, with x and y selected such that the band gap of the transition material rema in s constant throughout its thickness Amendment and Response Page 8 of 14 App li cation No 13/603,088 Conﬁrmation No 6649 Filed For GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT (as amended) 102 The method as deﬁned in claim 101, where in said graded i terlayer is composed of ni ne or more steps of layers of semiconductor material with monoto ni cally chang in g lattice constant and constant band gap 103 A method of form in g a triple j unction solar cell composed of I II -V compound semiconductor material compris ing form in g a top subcell hav in g a ﬁrst band gap, form in g a middle subcell hav in g a second band gap smaller than said ﬁrst band gap disposed over the top subcell, form in g a graded i terlayer disposed over the middle subcell that is compositionally graded to lattice match the middle subcell on one side and a bottom subcell on the other side, form in g the bottom subcell disposed over said graded m terlayer and hav in g a fourth band gap smaller than said second band gap such that said bottom subcell is lattice mismatched with respect to said middle subcell, form in g a semiconductor contact layer composed of GaAs over the top subcell, deposit in g a metal contact layer inc lud in g a germa ni um layer and a palladium layer over the semiconductor contact layer, and heat in g the metal contact layer at 210 degrees C or less to form an ohmic metal contact from the metal contact layer to the semiconductor contact layer hav in g a speciﬁc contact resistance of less than 2 x 10-4 ohms-cm2 104 The method as deﬁned in claim 103, where in the graded i terlayer is composed of InGaA 1As 105 The method as deﬁned in claim 103, where in the graded m terlayer has a band gap of approximately 1 5 eV throughout its thickness Amendment and Response Page 9 of 14 App li cation No 13/603,088 Conﬁrmation No 6649 Filed For GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT (as amended) 106 The method as deﬁned in claim 103, where in the graded in terlayer is composed of (In x Gai X)y Ali _y As, with x and y selected such that the band gap of the transition mate ri al rema ins constant throughout its thickness

Device structures

Layer stacks claimed or described, ordered top of device to substrate.

inverted metamorphic multijunction solar cell

Pd/Ge/Ti/Pd/Ag/Au metal contact stackmetal contact layer

GaAssemiconductor contact layer

InGaAs bottom subcellbottom subcell

InGaAlAs graded interlayergraded interlayer

middle_subcellmiddle subcell

InGa(Al)P top subcelltop subcell

Materials

Materials described outside the worked examples.

GaAs semiconductor contact layer

GaAs

Semiconductor Contact Layer

germanium layer

Metal Contact Layer Component

palladium layer

Process steps

Additional fabrication and treatment steps described in the patent.

Ohmic Contact Formation

Step 1

Temperature

210°C

Duration

35 min

Ambient

ambient atmosphere

Process details

Characterization

Measurements and analyses referenced in the patent, with their drawing references.

bandgap

Bandgap

FIG. 1 is a graph representing the bandgap of certain binary materials and their lattice constants; [027]

Figure references

fig_001

device performance measurement

Reported properties

Performance values and ranges asserted in the specification or claims.

Property	Value	Material
specific contact resistance (claimed upper bound)	0.0005 ohms-cm2	GaAsGePd

Why these are connected

Related documents with shared materials, methods, properties, or citations.

GALLIUM ARSENIDE SOLAR CELL WITH GERMANIUM/PALLADIUM CONTACT | Matter42 Literature