High resistivity aluminum antimonide radiation and alpha-particle detector

Abstract

Bulk Aluminum Antimonide (AlSb)-based single crystal materials have been prepared for use as ambient (room) temperature X-ray and Gamma-ray radiation and alpha-particle detection.

1 . A method of producing an ambient solid state detector, comprising: 
 preparing a growth melt of a solid crystal to be formed further comprising, weighing out a substantially pure Sb material having an oxygen concentration of greater than about 10 16  cm −3  and a substantially pure Al material in a predetermined proportion to form an AlSb compound, acid etching the Al material and an Sb ingot formed from the Sb material to substantially remove an oxide slag, pre-firing a preparing crucible at about 1200° C. to remove a moisture content and to ensure a complete outgassing of the preparing crucible, placing the Al material in the preparing crucible, placing the Sb ingot in a Tantalum cage having one or more wires adapted to hold the Sb ingot, the cage being removably attached to a stainless steel rod mounted through a port on a chamber lid, generating a vacuum inside a crystal grower, heating the preparing crucible to about 1000° C., introducing an Argon gas into the grower at a pressure within an enclosing chamber of about one atmosphere, raising a temperature of the preparing crucible above a melting temperature of AlSb, moving the stainless steel rod with the Sb ingot over a heat zone; and lowering the Sb ingot into the preparing crucible until it melts, wherein a resultant melt surface is substantially slag free,    rotating the preparing crucible,    inserting a seed crystal into a liquid comprising the growth melt,    forming the solid crystal from the liquid; and    temperature annealing subsequent to forming the solid crystal in an annealing crucible, wherein the temperature annealing step further comprises: combining a heated first mixture of a two-phase material comprising a first solid AlSb and a first liquid Al—Sb, the first mixture having a majority of Sb atoms, and a heated second mixture of a two phase material comprising a second solid AlSb and a second liquid Al—Sb, the second mixture having a majority of Al atoms, placing the solid crystal in the presence of the first and the second two phase mixtures; and annealing the solid crystal and the first and second mixtures under a constant temperature and a constant volume within the annealing crucible to produce a stoichiometric AlSb crystal material that is capable of detecting gamma or x-ray radiation or alpha particles, the AlSb crystal having an energy band-gap greater than about 1.40 eV, an electron and a hole mobility greater than about 100 cm 2 /Vs, a free carrier recombination time (τ) greater than about  10   −6  s, and a resistivity greater than about 10 7  Ω-cm.    
     
     
         2 . The method of  claim 1 , wherein the Sb material having an oxygen concentration of greater than about 10 16  cm −3  can be produced by melting the Sb material in a quartz crucible or ampoule.  
     
     
         3 . The method of  claim 1 , wherein the Sb material having an oxygen concentration of greater than about 10 16  cm −3  can be produced by melting the Sb material in a predetermined partial pressure of oxygen.  
     
     
         4 . The method of  claim 1 , wherein the Sb material having an oxygen concentration of greater than about 10 16  cm −3  can be produced by melting the Sb material and adding antimony oxide to the Sb melt.  
     
     
         5 . A method of producing an ambient solid state detector, comprising: 
 preparing a growth melt of a solid crystal to be formed, wherein the preparing growth melt step further comprises: placing a proportional amount of Sb having an oxygen concentration of greater than about 10 16  cm −3  and a proportional amount of Al into a preparing crucible without an acid etching step, creating a vacuum within an enclosing chamber, introducing an Argon gas at a pressure of one atmosphere, heating at a predetermined temperature the Al and the Sb to a liquid state Al—Sb, inserting one or more alumina-mixing rods removably attached to a stainless steel rod that is mounted through a port on a chamber lid while the preparing crucible is rotating, mixing with the one or more alumina-mixing rods for a predetermined mixing time range, lowering the temperature to about the melting temperature of a solid AlSb for a predetermined time period to stabilize the liquid Al—Sb, further lowering the temperature such that a dendritic crystal growth occurs from the one or more alumina-mixing rods, allowing the dendritic growth to continue until the growth substantially approaches a wall of the preparing crucible; and removing the one or more alumina-mixing rods having a solid lid of dendritic AlSb from a melt to produce the melt substantially free of a slag, 
 inserting a seed crystal into a liquid comprising the growth melt,  
 forming the solid crystal from the liquid; and  
 temperature annealing subsequent to forming the solid crystal in an annealing crucible, wherein the temperature annealing step further comprises: combining a heated first mixture of a two-phase material comprising a first solid dAlSb and a first liquid Al—Sb, the first mixture having a majority of Sb atoms, and a heated second mixture of a two phase material comprising a second solid AlSb and a second liquid Al—Sb, the second mixture having a majority of Al atoms, placing the solid crystal in the presence of the first and the second two phase mixtures; and annealing the solid crystal and the first and second mixtures under a constant temperature and a constant volume within the annealing crucible to produce a stoichiometric AlSb crystal material that is capable of detecting is capable of detecting gamma or x-ray radiation or alpha particles, the AlSb crystal having an energy band-gap greater than about 1.40 eV, an electron and a hole mobility greater than about 100 cm 2 /Vs, a free carrier recombination time (τ) greater than about  10   −6  s, and a resistivity greater than about 10 7  Ω-cm.  
   
     
     
         6 . The method of  claim 6 , wherein the Sb material having an oxygen concentration of greater than about 10 16  cm −3  can be produced by melting the Sb material in a quartz crucible or ampoule.  
     
     
         7 . The method of  claim 6 , wherein the Sb material having an oxygen concentration of greater than about 10 16  cm −3  can be produced by melting the Sb material in a predetermined partial pressure of oxygen.  
     
     
         8 . The method of  claim 6 , wherein the Sb material having an oxygen concentration of greater than about  10   16  cm −3  can be produced by melting the Sb material and adding antimony oxide to the Sb melt.  
     
     
         9 . An alpha-particle detector, comprising: 
 a high resistivity AlSb crystal having a bottom surface and a top surface, intended for operation at an operationally created e-field by a detector voltage applied thereto, the crystal generating a charge as a result of interacting alpha particles,    a first ohmic contact operationally connected to the top surface of the crystal; and    a second ohmic contact operationally connected to the bottom surface of the crystal,    wherein the e-field produces a sufficient charge collection to produce a representative alpha particle signal in an operationally connected circuitry that indicates an energy spectrum of the particles.    
     
     
         10 . The detector of  claim 9 , wherein the detector is capable of being operated at a room temperature greater than −196° C. to about 45° C.  
     
     
         11 . The detector of  claim 9 , wherein the detector is capable of being operated at a room temperature between about 20° C. and about 25° C.  
     
     
         12 . The detector of  claim 9 , wherein the crystal further comprises a III-V compound.  
     
     
         13 . The detector of  claim 9 , wherein the first and the second ohmic contact is a metal selected from Au, Ag, and Al.  
     
     
         14 . The detector of  claim 9 , wherein the first and the second ohmic contact is an alloy.  
     
     
         15 . The detector of  claim 9 , wherein the first ohmic contact further comprises an interposed doped semiconductor operationally connected to the top surface of said crystal and the second ohmic contacts further comprises an interposed oppositely doped semiconductor operationally connected to the bottom surface of said crystal.