Abstract: A solar cell fabrication procedure is described in which a silicon substrate having a layer of silicon nitride on one side is selectively coated with a paste that contains silver metal and a glass frit. Upon heating to a temperature in excess of 760 degrees C. for a time not exceeding about 20 seconds, the glass penetrates the silicon nitride and the substrate surface is metallized by the silver metal, with the result that the finished solar cell has a fill factor of at least about 0.75 even though the paste contains no phosphorus.

Abstract: A machine and method are provided for applying a solder paste to a solar cell or other semiconductor device. The machine comprises (1) a conveyor means having at least one cell-holding means for holding a photovoltaic solar cell, (2) drive means for moving the conveyor means stepwise so as to shift said cell-holding means in turn from a first cell loading position to a second cell pasting position and then to a cell unloading position, (3) selectively operable solder paste dispensing means for applying solder paste to a cell located at said second cell pasting position, (4) means for selectively operating said drive means and said paste dispensing means so as to (a) convey a cell from said loading position to said cell pasting position, (b) cause said paste-dispensing means to dispense solder paste onto a cell in said cell pasting position, and (c) convey the cell with the dispensed solder paste from said cell pasting position to said cell unloading position.

Abstract: An improved photovoltaic cell and a method for making such cells is provided. In a generic sense, the preferred method comprises the step of (1) applying a coating of an aluminum metal paste onto the rear surface of the substrate in a suitable rear contact pattern, (2) applying a layer of a glass frit paste so as to envelop the rear contact, and (3) firing those pastes so as to form a rear contact protected by a glass overcoating. A front contact also is formed by applying a silver metal/glass frit paste onto the anti-reflection coating in a related front contact pattern. The front and rear contacts may be fired simultaneously or in two different steps. However, a single firing method is preferred because thicker aluminum contacts are possible.

Abstract: An improved solar cell of the type including a semiconductor substrate having a shallow p-n junction adjacent its front surface, a rear electrode affixed in adherent mechanical and electrical contact with the rear surface of the semiconductor substrate, and a front generally grid-shaped electrode including an array of narrow, elongate, parallel fingers and at least one bus bar extending at right angles to the fingers in electrical contact therewith affixed in mechanically adherent and low resistance electrical contact with the front surface of the semiconductor substrate. The improvement includes the removal of the bus bar portion of the front grid-shaped electrode from intimate mechanical and electrical contact with the front surface of the semiconductor substrate.

Abstract: Silicon solar cells are made by subjecting semiconductor substrates to a diffusion junction forming process wherein a liquid source material containing a selected dopant is sprayed onto one side of the substrates, and thereafter the substrates are fired in an oxygen-containing environment under conditions calculated to cause the dopant to diffuse into the substrates so as to form a shallow p-n junction in each substrate.

Abstract: A solar energy power source is provided comprising at least two flat photovoltaic panels disposed in co-planar side-by-side relation and an improved support structure for supporting the panels for pivotal movement on a pivot axis that extends transversely of the panels, the improved structure including a single selectively operable drive means for pivoting all of the panels simultaneously and by the same amount of angular displacement.

Abstract: Photovoltaic cells with silver-rich thick film electrical contacts having superior thermal aging properties are disclosed. The silver-rich contacts are formed by firing a silver ink or paste wherein substantially all of the silver in the ink or paste before firing is in the form of spherical particles. Preferably inter-cell connections to the contacts are accomplished using a tin and silver solder paste comprising between about 96% tin/4% silver and 98% tin/2% silver. Solar cells having contacts incorporating the present invention exhibit the capability of withstanding temperatures in the range of 150.degree. C. with little or no thermal degradation of contact peel strength in the region of the solder bonds.

Abstract: A method and apparatus for producing crystalline substrate for use in fabricating solid state electronic devices. A hollow crystalline body is grown from a melt containing a dopant and a P-N junction is formed in said crystalline body as it is being grown. Then the hollow body is severed to provide individual solar cell substrates.

Abstract: A method of applying metallized contacts to the surfaces of semiconductor substrates using a conventional pad printing device. Standard screen printing inks diluted 2-30 weight percent with an appropriate solvent have been satisfactorily used to accomplish the method. For certain contact configurations, portions of the surface of the substrate are covered with a Mylar mask during the pad printing process. The method makes it possible to form a metallized contact having a uniform thickness on an uneven substrate surface, e.g., the surface of a silicon substrate produced by the EFG method.

Abstract: A method and apparatus are provided for forming grid electrodes for solar cells, the method and apparatus essentially involving dispensing a viscous ink through a hollow pen tip onto a selected horizontally oriented solar cell blank, so that the discharged ink forms a ribbon or line on the blank, with the pen tip being spaced far enough above the solar cell blank so that it does not ride on the deposited ribbon or line, whereby the width and height of the written ribbon or line are not determined by the o.d. of the pen tip or any pressure exerted by the pen tip.

Abstract: Nickel is introduced into the construction of the rear electrical contacts on silicon solar cells to reduce contact resistance between the aluminum contact material and the silver pads. In one embodiment, the nickel is applied as an intermediate layer between the silicon substrate and each silver pad. In a second and preferred embodiment, the nickel is incorporated into the silver ink that is used to make the soldering pads.

Abstract: A terminal connection for a solar cell device includes a conductive terminal strip protruding from the rear wall of the device and provided with a hole. An insulating convex/concave member is secured to the rear wall and is provided with an aperture which is positioned so that the hole in the strip extends across the aperture. The terminal strip extends between the insulating member and a nut received by the insulating member, with the nut being captured between the insulating member and the rear wall of the solar cell device. A connector member having a metal tube which is forged into electrical and mechanical connection with an exposed portion of a cable core is mechanically fastened to the terminal strip by a fastener which is screwed into the nut, whereby the terminal strip makes electrical contact between the cable and the solar device.

Abstract: A method and apparatus for producing crystalline substrates for use in fabricating solid state electronic devices. A hollow crystalline body is grown from a melt containing a dopant and a P-N junction is formed in said crystalline body as it is being grown. Then the hollow body is severed to provide individual solar cell substrates.

Abstract: A novel capillary die and crystal growing method are provided for growing a hollow crystalline body by EFG. Inner and outer annular moats surround the die tip. Passageways are provided for supplying melt to those moats from a crucible, so that melt in said moats will wet and cover the inner and outer exterior surfaces of the die tip during growth of a hollow crystalline body. The novel die may be constructed so as to have a lower die tip and a shorter capillary than EFG dies heretofore used to successfully grow hollow bodies. The die design facilitates keeping the temperature of the die tip substantially uniform about its circumference, thereby improving the uniformity of thickness of the wall of the crystalline body grown from a film of melt on the die tip. The moats reduce the likelihood of the growth process being interrupted or adversely affected by flooding of the die.

Abstract: A system for repeatedly supplying a predetermined quantity of solid particulate material, e.g. solid, spherical silicon particles, to a location remote from the area where the particulate material is stored. The system includes a container for storing solid particulate material, a receiving chamber coupled with the container and sized and configured to admit only a predetermined quantity of particulate material from the container, and means for applying at least one stream of a pressurized fluid so as to entrain and transport said predetermined quantity of particulate material from the receiving chamber to the remote location.

Abstract: A control system for controlling the operation of a system for replenishing the melt in the crucible of an apparatus for growing tubular crystalline bodies of a selected material. The melt replenishment system comprises a container for storing solid particles of said selected material and a dispenser for transporting the particles from the container to the crucible. The control system controls the rate at which the dispenser transports particles from the container to the crucible based on the weight of the solid particles stored in the container, the weight of the crystalline body, and the pressure inside the crystalline body. Additionally, the control system may be adapted to control the temperature of the crucible heater of the apparatus. Compensation is provided by this invention for weight measurement errors that are created by pressure fluctuations within the tubular crystalline body.

Abstract: A solar cell fabrication procedure is described in which an excimer laser is used to cut a trench in a flat solar cell substrate so as to electrically isolate front and back regions of the substrate. The trench is cut around the perimeter of the cell. The advantage of using an excimer laser is that it will ablate a trench without diffusing conductive material deeper into the cell.

Abstract: Photovoltaic cells with silver-rich thick film electrical contacts and superior thermal aging properties are disclosed. Electrical wires are bonded to the silver-rich thick film contacts using a tin and silver solder paste comprising between about 96% tin/4% silver and 98% tin/2% silver. Solar cells having soldered connections incorporating the present invention exhibit the capabilty of withstanding temperatures in the range of 150.degree. C. with little or no deterioration of the solder bonds for periods far longer than conventionally prepared cells.

Abstract: A novel capillary die and crystal growing method are provided for growing a hollow crystalline body by EFG. Inner and outer annular moats surround the die tip. Passageways are provided for supplying melt to those moats from a crucible, so that melt in said moats will wet and cover the inner and outer exterior surfaces of the die tip during growth of a hollow crystalline body. The novel die may be constructed so as to have a lower die tip and a shorter capillary than EFG dies heretofore used to successfully grow hollow bodies. The die design facilitates keeping the temperature of the die tip substantially uniform about its circumference, thereby improving the uniformity of thickness of the wall of the crystalline body grown from a film of melt on the die tip. The moats reduce the likelihood of the growth process being interrupted or adversely affected by flooding of the die.

Abstract: A control system for controlling the operation of an apparatus for growing tubular crystalline bodies. The control system comprises a weight sensor for measuring the weight of the crystal, a length sensor for measuring the length of the crystal, a pressure sensor for measuring the pressure inside the crystal, and a controller coupled to the weight, length and pressure sensors for controlling the operation of the crystal growing apparatus. The controller is coupled to the die heater of the apparatus for controlling the temperature of melt contained in the crucible of the apparatus based on the outputs of the weight, length and pressure sensors. To ensure the wall of the tubular crystalline body is maintained at a substantially uniform thickness, precise measurement of the weight of the body must be made. Compensation is provided by this invention for weight measurement errors that are created by pressure fluctuations within the tubular crystalline body.