Intersubband detector with avalanche multiplier region

Abstract

A photodetector for use at wavelengths of 2 μm and longer has an intersubband absorption region to provide absorption at wavelengths beyond 2 μm, integrated with an avalanche multiplier region to provide low-rise gain. In one particular design, the intersubband absorption region is a quantum-confined absorption region (e.g., based on quantum wells and/or quantum dots).

1 . A photodetector comprising: an intersubband absorption region for absorbing optical radiation at a wavelength of 2 .mu.m or greater to generate carriers based on an intersubband transition; and an avalanche multiplier region electrically coupled to receive and multiply the carriers generated in the intersubband absorption region.  
     
     
         2 . The photodetector of  claim 1  wherein the intersubband absorption region comprises: a quantum-confined absorption region.  
     
     
         3 . The photodetector of  claim 2  wherein the quantum-confined absorption region comprises a quantum well.  
     
     
         4 . The photodetector of  claim 2  wherein the quantum-confined absorption region comprises an array of quantum dots.  
     
     
         5 . The photodetector of  claim 2  wherein the quantum-confined absorption region comprises a dot-in-well (DWELL) absorption region.  
     
     
         6 . The photodetector of  claim 1  further comprising: an n-i-n structure including the intersubband absorption region; a semiconductor structure including the avalanche multiplier region; and a tunnel junction interface between the n-i-n structure and the p-i-n structure.  
     
     
         7 . The photodetector of  claim 6  wherein the semiconductor structure comprises: a p-i-n structure.  
     
     
         8 . The photodetector of  claim 6  wherein the semiconductor structure comprises: a heterostructure.  
     
     
         9 . The photodetector of  claim 1  wherein the avalanche multiplier region receives carriers of only one type from the intersubband absorption region.  
     
     
         10 . The photodetector of  claim 1  wherein the intersubband absorption region comprises: an impurity level detector.  
     
     
         11 . The photodetector of  claim 1  further comprising: electrical contacts for applying a first electric field across the intersubband absorption region and a second electric field across the avalanche multiplier region.  
     
     
         12 . The photodetector of  claim 1  further comprising: a GaAs substrate, wherein the intersubband absorption region and the avalanche multiplier region are integrated on the GaAs substrate.  
     
     
         13 . The photodetector of  claim 1  wherein the intersubband absorption region and the avalanche multiplier region are adapted for Geiger mode operation.  
     
     
         14 . (canceled)  
     
     
         15 . (canceled)