Abstract:
An apparatus for liquid phase epitaxial film growth includes a mother boat for supporting a substrate, a melt boat slidable on the mother boat for containing a melt and selectively bringing the substrate and the melt into contact, and a lid for opening and closing the melt boat. The mother boat is disposed in a quartz tube and push rods extend into the tube for sliding the lid to open and close the melt boat.
Abstract:
A method of making symmetrical mercury cadmium telluride layers by epitaxial growth on a cadmium telluride substrate, performed inside a reactor with two communicating zones, kept at different and controlled temperatures. Growth solution is directly prepared inside the reactor by submitting to a specific thermal cycle a weighed tellurium quantity, a saturating cadmium telluride substrate and a mercury bath.
Abstract:
A semiconducting photodiode for detecting light at a predetermined wavelength includes a first semiconducing region having a first conductivity type which is a quaternary alloy of Hg, Mn, Cd, and Te. A second semiconducting region having a second conductivity type electrically contacts the first semiconducting region, such that a semiconducting junction is formed between the first and second regions. The relative proportions of Hg, Mn, and Cd in the first region are selected so that the bandgap energy of the first region is approximately equal to the spin orbit splitting energy of the first region at the desired wavelength.
Abstract:
A layer of HgCdTe (15) is epitaxially grown onto a CdTe substrate (5). A HgTe source (3) is spaced from the CdTe substrate (5) a distance of between 0.1 mm and 10 mm. The substrate (5) and source (3) are heated within a temperature range of between 500.degree. C. and 625.degree. C. for a processing step having a duration of between 5 minutes and 4 hours. During at least 5 minutes of this processing step, the substrate (5) is made to have a greater temperature than the source (3). Preferably the substrate (5) is never at a lower temperature than the source (3). The source (3) and substrate (5) are heated together in a thermally insulating, reusable ampoule (17). The CdTe substrate (5) is preferably a thin film epitaxially grown on a support (10) e.g., of sapphire or GaAs. When support (10) is not used, the CdTe substrate (5) is polished; and sublimation and solid state diffusion growth mechanisms are present in the growth of the HgCdTe (15). Means are disclosed for preventing contamination of the reactants during HgTe (3) synthesis and bulk CdTe wafer (5) polishing.
Abstract:
A thin passivating layer (14) of CdTe is formed on a layer of photoconductive HgCdTe (4) by means of electrochemical deposition. The photoconductive layer (4) is used as a cathode. A first anode (26) is fabricated of tellurium and a second anode (28) is fabricated of an inert substance such as graphite. An electrolyte (30) comprises an aqueous solution of CdSO.sub.4 and unsaturated TeO.sub.2. Alternatively, electrolyte (30) can be saturated with TeO.sub.2, in which case a first anode is fabricated of an inert substance, and an optional second anode is fabricated of cadmium. After purifying the cathode (1) and the electrolyte (30), cadmium and tellurium are simultaneously deposited upon cathode (1). Stoichiometric balance is maintained to maximize the resistivity of the passivating CdTe layer (14). This is accomplished by regulating the deposition voltage of cathode (1) with respect to a saturated calomel electrode (22). In a first embodiment, an n-type region (16) is formed in the p-type photoconductive layer (4) subsequent to electrochemical deposition of the passivating CdTe layer (14). In a second embodiment, the n-type region (16) is formed in the p-type layer (4) prior to electrochemical deposition of the CdTe passivating layer (14).
Abstract:
The operating frequency of an IMPATT diode depends on the width of the depletion region formed during operation. The frequency of high efficiency GaAs IMPATT diodes comprising a non-uniformly doped depletion region contacted by a rectifying barrier can be more precisely fixed by forming a "clump" of charge at exactly the depth below the surface contacted by the rectifying barrier corresponding to the desired depletion region.
Abstract:
A method of positioning elements or additional technological levels (1) on the incident surface of an infrared detector of hybridized type, said detector being formed of a detection circuit (1, 10) comprising an array network of photosensitive sites (2) for the wavelength ranges of interest, hybridized on a read circuit (4), said detection circuit resulting from the epitaxial growth of a detection material on a substrate, comprising forming within the detection circuit (1, 10) indexing patterns (7, 14) by marking of the growth substrate.
Abstract:
A method and apparatus for an amount of Cu or Sb dopant incorporated into a zinc-based layer as the layer is being formed. The layer is formed over a coated substrate using an electrochemical deposition (ECD) process. In the ECD process, the bias voltage and plating solution composition may be systematically changed during the electrochemical deposition process to change the amount of Cu or Sb dopant incorporated into the plated layer.
Abstract:
An improved photovoltaic device and methods of manufacturing the same that includes an interface layer adjacent to a semiconductor absorber layer, where the interface layer includes a material in the semiconductor layer which decreases in concentration from the side of the interface layer contacting the absorber layer to an opposite side of the interface layer.