Pressure sensor

Abstract

A pressure sensor is provided. The pressure sensor includes a multi-layer laminate comprising a substrate and a semiconductor layer, wherein the substrate comprises single crystal or quasi-single crystal aluminum oxide, and a portion of the substrate that is spaced from a peripheral edge is wet etched to form an inwardly facing sidewall that defines a volume; and a substrate to which the multi-layer laminate is secured. The volume is an enclosed volume further defined by a substrate surface.

1 . A pressure sensor, comprising: 
 a multi-layer laminate comprising a substrate and a semiconductor layer, wherein the substrate comprises single crystal or quasi-single crystal aluminum oxide, and a portion of the substrate that is spaced from a peripheral edge is wet etched to form an inwardly facing sidewall that defines a volume; and    a substrate to which the multi-layer laminate is secured, wherein the volume is an enclosed volume further defined by a substrate surface.    
   
   
       2 . The sensor as defined in  claim 1 , wherein and the semiconductor layer comprises gallium nitride.  
   
   
       3 . The sensor as defined in  claim 1 , further comprising one or more ohmic contacts, or a metallic reflector layer, or both.  
   
   
       4 . The sensor as defined in  claim 1 , wherein a useful operating temperature range is greater than about 150 degrees Celsius.  
   
   
       5 . The sensor as defined in  claim 1 , wherein the sidewall is curved.  
   
   
       6 . A sensor, comprising an article capable of generating a response to a pressure change to which the sensor is subject, and the article comprises: 
 a multi-layer laminate comprising a substrate and a semiconductor layer, wherein the substrate comprises single crystal or quasi-single crystal aluminum oxide, and    a portion of the substrate that is spaced from a peripheral edge has an inwardly facing sidewall having a surface that defines a portion of a volume; the volume is an enclosed volume further defined by a substrate surface and a semicondutor layer surface; and    the semiconductor layer is a single crystal or a quasi single crystal and has an at least partially exposed second surface, the second surface has one or more property selected from the group consisting of:    the second surface is free of gallium metal;    the second surface is free of aluminum metal;    the second surface is free of both gallium metal and aluminum metal;    the second surface has a plurality of pendant fluoro groups chemically bonded thereto;    the second surface has potassium ions, sodium ions, or both diffused therein to a depth of less than about 5 micrometers; and    the second surface has an adjacent, unexposed portion of the etched single crystal substrate or quasi single crystal substrate, wherein un-etched portions of the substrate have a sidewall surface having a curvature in a range of from about 15 degrees to about 45 degrees.    
   
   
       7 . The sensor as defined in  claim 6 , wherein the second surface is free of gallium metal; the exposed surface is free of aluminum metal; or the exposed surface is free of both gallium metal and aluminum metal.  
   
   
       8 . The sensor as defined in  claim 6 , wherein the second surface has a plurality of pendant fluoro groups chemically bonded thereto.  
   
   
       9 . The sensor as defined in  claim 6 , wherein the second surface has potassium ions, sodium ions, or both potassium ions and sodium ions diffused therein to a depth of less than about 5 micrometers.  
   
   
       10 . The sensor as defined in  claim 6 , wherein the second surface has an adjacent, unexposed portion of the etched single crystal substrate or quasi single crystal substrate, wherein un-etched portions of the substrate have a sidewall surface having a curvature in a range of from about 15 degrees to about 45 degrees.  
   
   
       11 . The sensor as defined in  claim 6 , wherein the single crystal or the quasi-single crystal comprises gallium nitride.  
   
   
       12 . The sensor as defined in  claim 6 , wherein the average thickness of the laminate is less than about 70 micrometers.  
   
   
       13 . The sensor as defined in  claim 12 , wherein the average thickness of the laminate is in a range of from about 0.1 micrometers to about 20 micrometers.  
   
   
       14 . The sensor as defined in  claim 12 , wherein the average thickness of the laminate is greater than about 50 micrometers.  
   
   
       15 . The sensor as defined in  claim 14 , wherein the average thickness of the laminate is greater than about 325 micrometers.  
   
   
       16 . The sensor as defined in  claim 6 , wherein the semicondutor layer has a dislocation density of less than about 1000 per square centimeter.  
   
   
       17 . The sensor as defined in  claim 6 , wherein the semicondutor layer has an oxygen impurity concentration of less than 3×10 18  cm −3 .  
   
   
       18 . The sensor as defined in  claim 6 , wherein the sensor is capable of sensing a pressure change proximate to the semicondutor layer at a temperature greater than 100 degrees Celsius.  
   
   
       19 . The sensor as defined in  claim 18 , wherein the sensor is capable of sensing at a temperature greater than 150 degrees Celsius.  
   
   
       20 . The sensor as defined in  claim 18 , wherein the sensor is capable of sensing at a temperature greater than 200 degrees Celsius.  
   
   
       21 . The sensor as defined in  claim 6 , further comprising electrical contacts.