Photodiode Array, Method For Manufacturing The Same, And The Optical Measurement System Thereof

Abstract

A photodiode array for near infrared rays that includes photodiodes having a uniform size and a uniform shape, has high selectivity for the wavelength of received light between the photodiodes, and has high sensitivity with the aid of a high-quality semiconducting crystal containing a large amount of nitrogen, a method for manufacturing the photodiode array, and an optical measurement system are provided. The steps of forming a mask layer 2 having a plurality of openings on a first-conductive-type or semi-insulating semiconductor substrate 1, the openings being arranged in one dimension or two dimensions, and selectively growing a plurality of semiconductor layers 3 a, 3 b, and 3 c including an absorption layer 3 b in the openings are included.

1 . A photodiode array comprising: 
 a first-conductive-type or semi-insulating semiconductor substrate;    an insulating mask layer disposed on the semiconductor substrate and having a plurality of openings; and    semiconductor layers disposed in each of the openings, the semiconductor layers including an absorption layer,    wherein the absorption layer includes a pn junction.    
   
   
       2 . The photodiode array according to  claim 1 , further comprising a high-concentration semiconductor layer of a first-conductive-type disposed between the semiconductor substrate and the mask layer having the openings in which the semiconductor layers including the absorption layer are disposed.  
   
   
       3 . The photodiode array according to  claim 2 , further comprising: 
 first electrodes to be connected to the tops of the semiconductor layers; and    a second electrode to be connected to a surface of the semiconductor substrate opposite a surface on which the mask layer and the semiconductor layers including the absorption layer are disposed,    wherein the semiconductor substrate is of a first-conductive-type.    
   
   
       4 . The photodiode array according to  claim 2 , further comprising: 
 first electrodes to be connected to the tops of the semiconductor layers; and    a second electrode to be connected to the high-concentration semiconductor layer of a first-conductive-type.    
   
   
       5 . The photodiode array according to any one of  claims 1  to  4 , wherein the shape of the semiconductor layers including the absorption layer varies from one opening to another.  
   
   
       6 . The photodiode array according to  claim 5 , wherein at least the absorption layer of the semiconductor layers including the absorption layer is composed of a group III-V compound semiconductor containing nitrogen.  
   
   
       7 . The photodiode array according to  claim 5 , wherein at least the absorption layer of the semiconductor layers including the absorption layer is composed of a group Ill-V compound semiconductor containing antimony.  
   
   
       8 . The photodiode array according to  claim 5 , wherein the absorption layer has a multiple quantum well structure of InGaAs and GaAsSb.  
   
   
       9 . The photodiode array according to  claim 5 , wherein the absorption layer has a multiple quantum well structure of GaAs 1-x-y Sb y N x  (0≦x≦0.02) and a group Ill-V compound semiconductor containing nitrogen.  
   
   
       10 . The photodiode array according to  claim 5 , wherein the absorption layer has a multiple quantum well structure of InGaAs and GaAsSb, the InGaAs has a lattice constant smaller than that of the semiconductor substrate, the GaAsSb has a lattice constant larger than that of the semiconductor substrate, and the average lattice constant of the multiple quantum well structure is matched with that of the semiconductor substrate within 0.2%.  
   
   
       11 . An optical measurement system, comprising: 
 a plurality of photodetectors disposed on a common semiconductor substrate and having different absorption edge wavelengths,    wherein the optical measurement system analyzes the characteristics of signal light by detecting a difference in sensitivity of the photodetectors resulting from different absorption edges.    
   
   
       12 . A method for manufacturing a photodiode array, comprising the steps of: 
 forming a mask layer having a plurality of openings on a semiconductor substrate, the openings being arranged in one dimension or two dimensions; and    selectively growing semiconductor layers including an absorption layer in each of the openings.    
   
   
       13 . The method for manufacturing a photodiode array according to  claim 12 , wherein the plurality of openings have the same shape or different shapes.  
   
   
       14 . The method for manufacturing a photodiode array according to  claim 9 , wherein the mask layer is composed of silicon nitride.  
   
   
       15 . ) The method for manufacturing a photodiode array according to  claim 9 , further comprising the step of: 
 forming a pn junction in the absorption layer,    wherein the selective growth is performed while the semiconductor layers are doped with an impurity to form the pn junction, or the absorption layer and its overlying layer(s) are doped with an impurity after the step of selective growth.    
   
   
       16 . The method for manufacturing a photodiode array according to  claim 10 , wherein the mask layer is composed of silicon nitride.