Abstract:
A method for fabricating a photovoltaic device includes applying (206) a diblock copolymer layer on a substrate and removing a first polymer material from the diblock copolymer layer to form a plurality of distributed pores. A pattern forming layer is deposited (212) on a remaining surface of the diblock copolymer layer and in the pores in contact with the substrate. The diblock copolymer layer is lifted off (214) and portions of the pattern forming layer are left in contact with the substrate. The substrate is etched (216) using the pattern forming layer to protect portions of the substrate to form pillars in the substrate such that the pillars provide a radiation absorbing structure in the photovoltaic device.
Abstract:
A semiconductor is disclosed with a substrate doped with a substrate doping. There is a crystalline semiconductor layer disposed on a front side of the substrate. The crystalline semiconductor layer has a layer doping. The substrate doping changes to the layer doping within a 100 angstrom transition region. In alternative embodiments, the layer doping has novel profiles. In other alternative embodiments, the substrate has a crystalline semiconductor layers disposed on each of a front and a back side of the substrate. Each of the crystalline semiconductor layers has a respective layer doping and each of these layer dopings changes to the substrate doping within a respective transition region less than 100 angstroms thick. In still other embodiments of this invention, an amorphous silicon layer is disposed on a side of the crystalline semiconductor layer opposite the substrate. The amorphous silicon layer has an amorphous doping so that a tunnel junction is formed between the doped crystalline semiconductor layer and the amorphous layer. Manufacturing these structures at below 700 degrees Centigrade enables the narrow transition regions of the structures.
Abstract:
The invention provides a high temperature (about 1150 C or greater) annealing process for converting thick poly crystalline Si layers on the order of 1 μm to 40 μm on a single crystal seed layer into thick single crystal Si layers having the orientation of the seed layer, thus allowing production of thick Si films having the quality of single crystal silicon at high rates and low cost of processing. Methods of integrating such high temperature processing into solar cell fabrication are described, with particular attention to process flows in which the seed layer is disposed on a porous silicon release layer. Another aspect pertains to the use of similar high temperature anneals for poly-Si grain growth and grain boundary passivation. A further aspect relates to structures in which these thick single crystal Si films and passivated poly-Si films are incorporated.
Abstract:
Embodiments of the present invention provide a solar energy converter, which includes a silicon layer having at least two regions of a first and a second conductivity type that form a P-N junction, at least a portion of the silicon layer being porous, and pores in the portion of porous silicon containing a semiconductor material, the semiconductor material being different from silicon; and a first and a second electrode being placed at a bottom and a top surface of the silicon layer respectively. Methods of manufacturing the same are also provided.
Abstract:
A semiconductor-containing heterostructure including, from bottom to top, a IH-V compound semiconductor buffer layer, a III-V compound semiconductor channel layer, a HI-V compound semiconductor barrier layer, and an optional, yet preferred, IH-V compound semiconductor cap layer is provided. The barrier layer may be doped, or preferably undoped. The HI-V compound semiconductor buffer layer and the HI-V compound semiconductor barrier layer are comprised of materials that have a wider band gap than that of the pi-V compound semiconductor channel layer. Since wide band gap materials are used for the buffer and barrier layer and a narrow band gap material is used for the channel layer, carriers are confined to the channel layer under certain gate bias range. The inventive heterostructure can be employed as a buried channel structure in a field effect transistor.
Abstract:
A method is disclosed for forming a strained Si layer on SiGe, where the SiGe layer has improved thermal conductivity. A first layer (41) of Si or Ge is deposited on a substrate (10) in a first depositing step; a second layer (42) of the other element is deposited on the first layer in a second depositing step; and the first and second depositing steps are repeated so as to form a combined SiGe layer (50) having a plurality of Si layers and a plurality of Ge layers (41-44). The respective thicknesses of the Si layers and Ge layers are in accordance with a desired composition ratio of the combined SiGe layer. The combined SiGe layer (50) is characterized as a digital alloy of Si and Ge having a thermal conductivity greater than that of a random alloy of Si and Ge. This method may further include the step of depositing a Si layer (61) on the combined SiGe layer (50); the combined SiGe layer is characterized as a relaxed SiGe layer, and the Si layer (61) is a strained Si layer. For still greater thermal conductivity in the SiGe layer, the first layer and second layer may be deposited so that each layer consists essentially of a single isotope.
Abstract:
The present invention provides a method of fabricating a SiGe-on-insulator substrate in which lattice engineering is employed to decouple the interdependence between SiGe thickness, Ge fraction and strain relaxation. The method includes providing a SiGe-on-insulator substrate material comprising a SiGe alloy layer having a selected in-plane lattice parameter, a selected thickness parameter and a selected Ge content parameter, wherein the selected in-plane lattice parameter has a constant value and one or both of the other parameters, i.e., thickness or Ge content, have adjustable values; and adjusting one or both of the other parameters to final selected values, while maintaining the selected in-plane lattice parameter. The adjusting is achieved utilizing either a thinning process or a thermal dilution process depending on which parameters are fixed and which are adjustable.
Abstract:
A method for fabricating germanium-on-insulator (GOI) substrate materials, the GOI substrate materials produced by the method and various structures that can include at least the GOI substrate materials of the present invention are provided. The GOI substrate material include at least a substrate, a buried insulator layer located atop the substrate, and a Ge-containing layer, preferably pure Ge, located atop the buried insulator layer. In the GOI substrate materials of the present invention, the Ge-containing layer may also be referred to as the GOI film. The GOI film is the layer of the inventive substrate material in which devices can be formed.
Abstract:
Hemispheres (18) and spheres (28) are formed and employed for a plurality of applications. Hemispheres (18) are employed to form a substrate having an upper surface and a lower surface (12). The upper surface includes peaks of pillars (10) which have a base attached to the lower surface. The peaks have a density defined at the upper surface by an array of hemispherical metal structures (18) that act as a mask during an etch to remove substrate material down to the lower surface during formation of the pillars. The pillars are dense and uniform and include a microscale average diameter. The spheres are formed as independent metal spheres or nanoparticles for other applications.
Abstract:
An epitaxy method includes providing (402) an exposed crystalline region of a substrate material. Silicon is epitaxially deposited (404) on the substrate material in a low temperature process wherein a deposition temperature is less than 500 degrees Celsius. A source gas is diluted (408) with a dilution gas with a gas ratio of dilution gas to source gas of less than 1000.