Photovoltaic Cell With an Aluminium-Arsenic and Indium-Phosphorous Based Heterojunction, Associated Multi-Junction Cell and Associated Method

1 . A photovoltaic cell comprising a heterojunction with a base layer made from an Aluminium-Arsenic-based alloy and an emitter layer made from an Indium-Phosphorous based alloy wherein the emitter layer has a thickness smaller than 100 nm and acts as a passivation layer to prevent oxidation of the base layer and reduce surface recombination.

2 . The photovoltaic cell in accordance with claim 1 wherein the heterojunction is a p-i-n heterojunction and comprises at least one intrinsic sub-layer at the interface between the base layer and the emitter layer.

3 . The photovoltaic cell in accordance with claim 1 wherein the base layer is made of an Aluminium-Gallium-Arsenic “AlGaAs” alloy.

4 . The photovoltaic cell in accordance with claim 1 wherein the emitter layer is made of an Indium-Gallium-Phosphide “InGaP” alloy.

5 . The photovoltaic cell in accordance with claim 1 wherein the base layer comprises a graded Aluminium based alloy with an Aluminium percentage composition between about 20 to 55%.

6 . The photovoltaic cell in accordance with claim 5 wherein the base layer comprises a first sublayer made of AlGaAs with 25% of Aluminium doped with Beryllium and a second sub-layer made of an intrinsic graded AlGaAs with a percentage of Aluminium composition between about 25 to 30%.

7 . The photovoltaic cell in accordance with claim 1 wherein the base layer has a bandgap of about 1.7 eV and the emitter layer has a bandgap of about 1.9 eV.

8 . The photovoltaic cell in accordance with claim 1 comprising:

a front contact layer made of Gallium-Arsenic “GaAs” alloy doped with one among the following dopants:

Silicon “Si”,

Selenium “Se”,

Tellurium “Te”,

comprising a doping concentration comprised between 5.10 18 cm −3 and 5.10 19 cm −3

and comprising hewing a thickness comprised between 150 nm and 300 nm,

a window layer made of Aluminium-Indium-Phosphide “AlInP” alloy doped with one among the following dopants:

Silicon “Si”,

Selenium “Se”,

Tellurium “Te”,

comprising a doping concentration comprised between 5.10 18 cm −3 and 1.10 19 cm −3

and comprising a thickness comprised between 20 nm and 70 nm,

an emitter layer made of Indium-Gallium-Phosphide “InGaP” alloy which can be doped with one among the following dopants:

Silicon “Si”,

Selenium “Se”,

Tellurium “Te”,

comprising a doping concentration comprised between 1.10 16 cm −3 and 2.10 18 cm −3

and comprising a thickness between 20 nm and 100 nm,

a base layer made of Aluminium-Gallium-Arsenic “Al x Ga 1-x As” alloy with x comprised between 0 and 0.37 and doped with one among the following dopants:

Beryllium “Be”,

Carbon “C”,

Zinc “Zn”,

comprising a doping concentration comprised between 2.10 16 cm −3 and 5.10 17 cm −3

and comprising hewing a thickness comprised between 200 nm and 2000 nm,

a back surface field made of Aluminium-Gallium-Arsenic “Al x Ga 1-x As” alloy with x comprised between 0.4 and 0.8 and doped with one among the following dopants:

Beryllium “Be”,

Carbon “C”,

Zinc “Zn”,

comprising a doping concentration comprised between 5.10 18 cm −3 and 1.10 19 cm −3

and comprising a thickness between 20 nm and 120 nm,

a back contact layer made of Gallium-Arsenic “GaAs” alloy doped with one among the following dopants:

Beryllium “Be”,

Carbon “C”,

Zinc “Zn”,

comprising a doping concentration between 5.10 18 cm −3 and 1.10 19 cm −3

and comprising a thickness comprised between 150 nm and 300 nm.

9 . The photovoltaic cell in accordance with claim 1 comprising:

a front contact layer made of Gallium-Arsenic “GaAs” alloy doped with Silicon “Si” comprising a doping concentration comprised between 5.10 18 cm −3 and 2.10 19 cm −3 and comprising a thickness between 150 and 320 nm,

a window layer made of Aluminium-Indium-Phosphide “AlInP” alloy doped with Silicon “Si” comprising a doping concentration between 5.10 18 cm −3 and 2.10 19 cm −3 and comprising a thickness between 20 nm and 50 nm,

an undoped emitter layer made of Indium-Gallium-Phosphide “InGaP” comprising a thickness between 40 and 60 nm,

a base layer made of Aluminium-Gallium-Arsenic “Al 0.25 GaAs” alloy doped with Beryllium “Be” comprising a doping concentration between 1.10 16 cm −3 and 2.10 17 cm −3 and comprising a thickness between 400 nm and 2000 nm,

a back surface field made of Aluminium-Gallium-Arsenic “Al 0.51 GaAs” alloy doped with Beryllium “Be” comprising a doping concentration between 4.10 18 cm −3 and 1.10 19 cm −3 and comprising a thickness between 20 nm and 80 nm,

a back contact layer made of Gallium-Arsenic “GaAs” alloy doped with Beryllium “Be”, comprising a doping concentration between 5.10 18 cm −3 and 2.10 19 cm −3 and comprising a thickness between 150 nm and 300 nm.

10 . The photovoltaic cell in accordance with claim 8 wherein the base layer also comprises:

a front additional sub-layer made of undoped Aluminium-Gallium-Arsenic “Al x Ga 1-x As” with a graded concentration of Aluminium varying between 25% and 37% and comprising a thickness between 80 and 120 nm,

a back additional sub-layer made of Aluminium-Gallium-Arsenic “A x Ga 1-x As” with a graded concentration of Aluminium varying between 25% and 51% and doped with Beryllium “Be” with a doping concentration between 4.10 18 cm −3 and 6.10 18 cm −3 and comprising a thickness between 80 and 120 nm.

11 . The photovoltaic cell in accordance with claim 9 wherein the back contact layer also comprises:

a front additional sub-layer made of Aluminium-Gallium-Arsenic “Al x Ga 1-x As” with a graded concentration of Aluminium varying between 51% and 0% and doped with Beryllium “Be” comprising a doping concentration between 4.10 18 cm −3 and 6.10 18 cm −3 and comprising a thickness between 80 and 120 nm.

12 . A multi junction photovoltaic cell comprising a stack of at least a first and a second photovoltaic cells, with a front photovoltaic cell having a first bandgap and a second photovoltaic cell having a second bandgap lower than the first bandgap wherein at least the front photovoltaic cell is a photovoltaic cell in accordance with one of the previous claims.

13 . The multi junction photovoltaic cell in accordance with claim 12 comprising two photovoltaic cells wherein the second photovoltaic cell is a silicon-based cell having a bandgap of 1.1 eV.

14 . A method for manufacturing a photovoltaic cell or a tandem photovoltaic cell in accordance with claim 1 wherein at least some of the layers of the tandem photovoltaic cell are obtained based on a molecular beam epitaxy “MBE” process or a Metalorganic Chemical Vapor Deposition “MOCVD” process.