Abstract: A method of forming an ohmic contact and electron reflector on a surface of a CdTe containing compound film as may be found, for example in a photovoltaic cell. The method comprises forming a Cd-deficient, Te-rich surface region at a surface of the CdTe containing compound film; exposing the Cd-deficient surface region to an electron reflector forming material; forming the electron reflector; and laying down a contact layer over the electron reflector layer. The solar cell so produced has a Cd-deficient region which is converted to an electron reflector layer on the surface of a CdTe absorber layer, and an ohmic contact. A Cd/Te molar ratio within the Cd-deficient region decreases from 1 at an interface with the CdTe absorber layer to a value less than 1 towards the ohmic contact.

Abstract: A method of making a back contact to a Group IIB-VIA compound layer employed in a device such as a solar cell and in particular a CdTe solar cell. The method involves deposition of a contact buffer layer comprising an ionic conductor over a surface of a CdTe film, which is the absorber of the solar cell. A highly conductive contact layer is deposited over the contact buffer layer. In some examples, the compound device is a device such as a solar cell and in particular a CdTe solar cell in a sub-strate configuration or structure. The method involves deposition of a contact buffer layer comprising an ionic conductor on a surface of a highly conductive contact layer. A CdTe film, which is the absorber layer of the solar cell is then deposited over the contact buffer layer.

Abstract: Methods and apparatus are described for electrodeposition of Group IIB-VIA materials out of electrolytes comprising Group IIB and Group VIA species onto surfaces of workpieces. In one embodiment a method of electrodeposition is described wherein the control of the process is achieved by measuring an initial value of the electrodeposition current at the beginning of the process and adding Group VIA species into the electrolyte to keep the electrodeposition current substantially constant, such a within +/?10% of the initial value throughout the deposition period. In another embodiment an apparatus comprising multiple deposition chambers are described, each deposition chamber containing an anode and a workpiece, and wherein two thirds of the deposition chambers within the apparatus contain anodes comprising a substantially pure Group VIA element in their composition, and the rest of the deposition chambers contain anodes free from any Group VIA element in their composition.

Abstract: A method of fabricating a solar cell involves electroplating a Group IIB-VIA material as a first or sub-layer over a junction partner layer, and then forming a second layer, also of a Group IIB-VIA material over the sub-layer. Both the sub-layer and the second layer comprise Te. The electroplating is performed at relatively low temperatures, as for example, below 100° C. Forming the sub-layer by low temperature electroplating produces a small grained compact film that protects the interface between the sub-layer and the junction partner during the formation of the second layer. The second layer may be formed by physical vapor deposition or ink deposition. A solar cell has a first layer of a stoichiometric Group IIB-VIA material formed on a CdS film, and a second layer of a Group IIB-V1A material. Both the first and second layers contain Te. The first layer may comprise CdTe with a grain size small than 0.5 microns and the second layer may comprise CdTe with a grin size in the range of 1-5 microns.

Abstract: An integrated structure for solar modules may be formed by deposition of a transparent conductive material layer on a transparent support, forming scribe lines through the transparent conductive material layer, depositing a semiconductor window layer, depositing a solar cell absorber layer, depositing a first conductive layer, making cuts through the layers to expose a top surface of the transparent conductive material layer, depositing a second conductive layer and making isolation scribes that separate back contacts of adjacent solar cells from each other. Alternatively, two conductive films may be used with high resistance plugs, thereby permitting optimization of functions. The first film may be selected to optimize good ohmic contact with the absorber layer and/or to present a high diffusion barrier, whereas the second conductive film may be selected to optimize good ohmic contact with the transparent conductive material layer.

Abstract: A method of forming an ohmic contact and electron reflector on a surface of a CdTe containing compound film as may be found, for example in a photovoltaic cell. The method comprises forming a Cd-deficient, Te-rich surface region at a surface of the CdTe containing compound film; exposing the Cd-deficient surface region to an electron reflector forming material; forming the electron reflector; and laying down a contact layer over the electron reflector layer. The solar cell so produced has a Cd-deficient region which is converted to an electron reflector layer on the surface of a CdTe absorber layer, and an ohmic contact. A Cd/Te molar ratio within the Cd-deficient region decreases from 1 at an interface with the CdTe absorber layer to a value less than 1 towards the ohmic contact.

Abstract: Methods and apparatus are described for electrodeposition of Group IIB-VIA materials out of electrolytes comprising Group IIB and Group VIA species onto surfaces of workpieces. In one embodiment a method of electrodeposition is described wherein the control of the process is achieved by measuring an initial value of the electrodeposition current at the beginning of the process and adding Group VIA species into the electrolyte to keep the electrodeposition current substantially constant, such a within +/?10% of the initial value throughout the deposition period. In another embodiment an apparatus comprising multiple deposition chambers are described, each deposition chamber containing an anode and a workpiece, and wherein two thirds of the deposition chambers within the apparatus contain anodes comprising a substantially pure Group VIA element in their composition, and the rest of the deposition chambers contain anodes free from any Group VIA element in their composition.

Abstract: A thin film solar cell includes a buffer layer disposed between a transparent conductive layer and a junction partner layer. The solar cell has an absorber layer made from a Group II-VI compound which is in contact with the junction partner layer. The buffer layer is made from at least one of cadmium doped tin oxide, indium sulfide, tin doped indium sulfide, gallium sulfide and tin doped gallium sulfide.

Abstract: A method of forming an ohmic contact to a surface of a Cd and Te containing compound film as may be found, for example in a photovoltaic cell. The method comprises forming a Te-rich layer on the surface of the Cd and Te containing compound film; depositing an interface layer on the Te-rich layer; and laying down a contact layer on the interface layer. The interface layer is composed of a metallic form of Zn and Cu.

Abstract: Embodiments of the inventions provide methods and apparatus to electroplate films of tellurides such as CdTe, or its alloys on multiple large area workpieces. In one embodiment a method of forming a solar cell absorber film on multiple work pieces uses a self adjusting mechanism taking advantage of the high resistivity of the solar cell absorber film. Larger deposits of the plating material onto one workpiece, due for example, to non-uniformity of solution flow, results in larger resistance thus decreasing the current flowing through that workpiece. The decreased current then deposits less material over that workpiece. In another embodiment multiple workpieces can be electroplated using a single power supply in a single plating bath.

Abstract: A method of forming a metal telluride (MTe) film on a base where M is Cd and optionally additionally may include at least one of Zn, Hg, Mn and Mg, involves depositing a Te-rich precursor layer on a base and reaction of the Te-rich precursor layer with an M-containing material at elevated temperature. The Te-rich precursor film is one of a MTex compound film with an x value larger than 1, a composite film comprising MTe and Te, and a composite film comprising a MTex compound film with an x value larger than 1. In a preferred embodiment the Te-rich precursor layer is electrodeposited. In another preferred embodiment both the Te-rich precursor layer and the M-containing material are electrodeposited.

Abstract: A method of forming an ohmic contact to a surface of a Cd and Te containing compound film as may be found, for example in a photovoltaic cell. The method comprises forming a Te-rich layer on the surface of the Cd and Te containing compound film; depositing an interface layer on the Te-rich layer; and laying down a contact layer on the interface layer. The interface layer is composed of a metallic form of Zn and Cu.

Abstract: A method of fabricating a solar cell involves electroplating a Group IIB-VIA material as a first or sub-layer over a junction partner layer, and then forming a second layer, also of a Group IIB-VIA material over the sub-layer. Both the sub-layer and the second layer comprise Te. The electroplating is performed at relatively low temperatures, as for example, below 100° C. Forming the sub-layer by low temperature electroplating produces a small grained compact film that protects the interface between the sub-layer and the junction partner during the formation of the second layer. The second layer may be formed by physical vapor deposition or ink deposition. A solar cell has a first layer of a stoichiometric Group IIB-VIA material formed on a CdS film, and a second layer of a Group IIB-V1A material. Both the first and second layers contain Te. The first layer may comprise CdTe with a grain size small than 0.5 microns and the second layer may comprise CdTe with a grin size in the range of 1-5 microns.