摘要:
A method is provided for producing an n-type or p-type epitaxial layer using a doped substrate material. The method includes growing a substrate (12), preferably from a material to which an epitaxial layer can be lattice-matched. The substrate (12) is doped with a predetermined concentration of dopant (14). Preferably, the dopant (14) possesses the ability to rapidly diffuse through a material. An epitaxial layer (16) is grown upon the doped substrate (12). The epitaxial layer (16) and the doped substrate are annealed, thereby causing the dopant (14) to diffuse from the substrate (14) into the epitaxial layer (16).
摘要:
Methods of annealing Hg.sub.1-x Cd.sub.x Te slices (56) in a mercury reflux chamber (32, 34) with a mercury reservoir (52) at the bottom and condensation regions at the top (62) is disclosed. The chamber is heated by a furnace (44) that creates an annealing region encompassing both the reservoir and a holder (46) for the Hg.sub.1-x Cd.sub.x Te slices (56). In preferred embodiment methods reservoir (52) is heated to 270.degree. C. for two hours to sixty days. An annealing immediately after LPE growth by use of either mercury vapor from the melt or a separate reservoir is also disclosed.
摘要:
Methods of doping Hg.sub.1-x Cd.sub.x Te (50) with fast diffusing dopants by immersion in a mercury reservoir (32) doped with the desired dopants are disclosed. Also, methods of core annihilation of Hg.sub.1-x Cd.sub.x Te slices or ingots by immersion in a heated mercury reservoir are disclosed. Preferred embodiments include dopants such as copper in a mercury reservoir (32) that is heated to 270.degree. C. for a Hg.sub.1-x Cd.sub.x Te slice, and a reservoir (32) that is heated to 150.degree. C. for a thin film of Hg.sub.1-x Cd.sub.xn Te on a CdTe substrate.
摘要:
The disclosure relates to a method of forming samples of alloys of group II-VI compositions having minimum dislocations, comprising the steps of providing a sample of a group II-VI compound, providing an enclosed ampoule having the sample at one end portion thereof and a group II element of the compound at an end portion remote from the one end portion, heating the sample to a temperature in the range of 350 to the melting temperature of the compound for about one hour while maintaining the group II element at a temperature more than 200.degree. C. below the sample temperature, heating the group II element to a temperature from about 5.degree. to about 50.degree. C. below the temperature of the sample while maintaining the sample at a temperature in the range of 350.degree. to 650.degree. C. both of about 15 minutes to about 4 hours, and then stoichiometrically annealing the sample at a temperature below 325.degree. C.
摘要:
The disclosure relates to a method for removing the unwanted impurities from an HgCdTe alloy which consists of the steps of depositing a thin film on the order of from about 1 to about 100 microns in thickness of tellurium onto the backside of a mercury cadmium telluride bar to insure the presence of a substantial amount of excess tellurium on the backside of the alloy bar and allow the gettering mechanism to work. A protective film to shield the tellurium film from mercury ambient atmosphere is then optionally placed over the tellurium film. The protective film can be formed of a silicon oxide such as SiO and is preferably in the range of about 1000 angstroms to 10 microns or more in thickness. The bar with the tellurium and protective film thereon is then annealed at a temperature of less than 450.degree. C., preferably about 280.degree. C., for a period of from about one day to about four weeks in a saturated mercury atmosphere to allow the impurities in the alloy to diffuse to the backside thereof and into the tellurium layer. The bulk of the impurities will travel into the tellurium layer within a matter of several days at the preferred temperature noted hereinabove. The tellurium layer and protective film are then removed such as by grinding, etching or other appropriate method to remove the impurities from the alloy bar.
摘要:
The dislocation density near the surface of Hg.sub.1-x Cd.sub.x Te alloys is substantially reduced by annealing the material at around 600.degree. C. in a mercury saturated ambient for periods of four hours or more, prior to post annealing at lower temperatures to control the metal vacancy concentration. This procedure allows dislocation reduction by climb, reduces the concentration of metal vacancies which can collapse to form dislocation loops or contribute to dislocation multiplication, and reduces tellurium precipitates which contribute to dislocation multiplication during subsequent post annealing.
摘要:
A method of gettering impurities from substrates (304) such as CdTe and CdZnTe by formation of liquid droplets (306) of a lower melting point material such as Cd or Te on the substrate during an anneal. The droplets may form from the melting of a thin layer of the material which had been deposited on the substrate (304). A subsequent mechanical removal of the cooled and solidified droplets also removes the gettered impurities.
摘要:
A P-type substrate for infrared photo diodes can be produced by the present invention. A CdZnTe substrate is utilized. A first layer of HgCdTe is formed by liquid phase epitaxy on the substrate. A CdTe passivation layer is formed over the HgCdTe. A ZnS layer is formed over the CdTe layer. A noble metal is introduced into either the CdTe or ZnS layers. During a subsequent baking of the composite, the noble metal diffuses throughout the composite and into the HgCdTe layer.
摘要:
A hybrid focal plane array has p-n junction photodiodes formed in a substrate (10) of HgCdTe which is passivated by a cap layer (12) of Cd-rich CdTe. The active surface of the HgCdTe substrate is passivated by annealing at a temperature sufficient to support interdiffusion between the Cd-rich CdTe capping layer (12) and the HgCdTe substrate (10). Use of the CdTe capping layer (12) with a slight excess Cd maintains the surface of the HgCdTe substrate (10) in a metal-rich phase condition.
摘要:
The disclosure relates to a method for reducing impurity concentration in mercury cadmium telluride alloys wherein impurities are attracted to a region saturated with second phase tellurium during annealing in a saturated mercury atmosphere where the second phase tellurium and the impurities attracted thereto can be removed by polishing, etching, grinding, or the like.