Laser device and methods for manufacturing the same

Abstract

Provided is a laser device according to an embodiment of the inventive concept. The laser device includes: a semiconductor substrate; a germanium single crystal layer on the semiconductor substrate; and a pumping light source disposed on the germanium single crystal layer and configured to emit light toward the germanium single crystal layer, wherein the germanium single crystal layer receives the light to thereby output laser.

What is claimed is: 
     
         1 . A laser device, comprising:
 a semiconductor substrate;   a germanium single crystal layer on the semiconductor substrate; and   a pumping light source disposed on the germanium single crystal layer and configured to emit light toward the germanium single crystal layer,   wherein the germanium single crystal layer receives the light to thereby output laser.   
     
     
         2 . The laser device of  claim 1 , wherein the pumping light source has a silicon photonic crystal structure having a plurality of holes. 
     
     
         3 . The laser device of  claim 2 , further comprising:
 a first oxide film disposed between the pumping light source and the semiconductor substrate to cover the germanium single crystal layer; and   a second oxide film covering the pumping light source and filling the gap between the plurality of holes.   
     
     
         4 . The laser device of  claim 1 , wherein the pumping light comprises first and second regions which are doped with different impurities from each other. 
     
     
         5 . The laser device of  claim 4 , wherein a border between the first and second regions is positioned over the germanium single crystal layer. 
     
     
         6 . The laser device of  claim 4 , further comprising an intrinsic third region disposed between the first and second regions, wherein the third region vertically overlaps the germanium single crystal layer. 
     
     
         7 . The laser device of  claim 4 , further comprising:
 a first electrode connected with the semiconductor substrate;   a second electrode connected with the germanium single crystal layer;   a third electrode connected with the first region; and   a fourth electrode connected with the second region.   
     
     
         8 . The laser device of  claim 7 , further comprising an electrode junction layer disposed on the germanium single crystal layer to contact the second electrode, wherein the electrode junction layer has a doping type which is different from that of the semiconductor substrate and is the same as that of the germanium single crystal layer. 
     
     
         9 . The laser device of  claim 1 , wherein the semiconductor substrate comprises silicon. 
     
     
         10 . The laser device of  claim 1 , wherein the germanium single crystal layer is an optical resonator for amplifying light emitted from the pumping light source to output laser. 
     
     
         11 . A method for manufacturing a laser device, the method comprising:
 providing a substrate having a lower semiconductor layer, an upper semiconductor layer, and a first oxide film disposed between the lower and upper semiconductor layers;   forming first and second regions which have doping types different from each other by implanting impurities into the upper semiconductor layer;   forming a silicon photonic crystal structure having a plurality of holes by etching the upper semiconductor layer;   forming an opening exposing the lower semiconductor layer by removing the first oxide film disposed under the silicon photonic crystal structure; and   forming a germanium single crystal layer in the opening.   
     
     
         12 . The method of  claim 11 , wherein the forming of the germanium single crystal layer comprises:
 forming a second oxide film covering the silicon photonic crystal structure and a portion of the lower semiconductor layer exposed through the opening;   forming a mask pattern on the silicon photonic crystal structure;   removing the second oxide film covering a portion of the lower semiconductor layer through an etching process; and   growing the germanium single crystal layer in the opening.   
     
     
         13 . The method of  claim 12 , wherein the growing of the germanium single crystal layer comprises a reduced pressure chemical vapor deposition (RPCVD) process, a low pressure chemical vapor deposition (LPCVD) process, or an ultra-high vacuum chemical vapor deposition (UHVCVD) process,
 wherein a process gas used during the growing of the germanium single crystal layer passes through the holes to move into the opening.   
     
     
         14 . The method of  claim 11 , further comprising forming a first electrode connected with the semiconductor substrate, a second electrode connected with the germanium single crystal layer, a third electrode connected with the first region, and a fourth electrode connected with the second region. 
     
     
         15 . The method of  claim 14 , wherein the forming of the first to fourth electrodes comprises:
 forming a third oxide film configured to fill the holes and covers the silicon photonic crystal structure;   forming a first contact hole exposing a portion of an upper surface of the lower semiconductor layer;   forming a second contact hole exposing a portion of an upper surface of the germanium single crystal layer;   forming third and fourth contact holes which respectively expose portions of upper surfaces of the first and second regions; and   filling a conductive material into the first to fourth contact holes.   
     
     
         16 . The method of  claim 14 , further comprising forming an electrode junction layer on the germanium single crystal layer, wherein the second electrode contacts the electrode junction layer. 
     
     
         17 . A method for manufacturing a laser device, comprising:
 providing a substrate having a lower semiconductor layer, an upper semiconductor layer, and a first oxide film disposed between the lower and upper semiconductor layers;   implanting impurities having different conductive types into the upper semiconductor layer;   forming a silicon photonic crystal structure having a plurality of first holes by etching a central region of the upper semiconductor layer;   forming an opening exposing the lower semiconductor layer by removing the first oxide film disposed under the silicon photonic crystal structure;   forming a germanium single crystal layer and an electrode junction layer on the germanium single crystal layer in the opening;   forming a second oxide film filled between the silicon photonic crystal structure and the germanium single crystal layer;   forming a plurality of second holes by etching a peripheral region of the upper semiconductor layer; and   forming a third oxide film filled into the first and second holes which are formed on the central region and the peripheral region and configured to cover the upper semiconductor layer.   
     
     
         18 . The method of  claim 17 , further comprising forming a first electrode connected with the lower semiconductor layer, a second electrode connected with the electrode junction layer, and third and fourth electrodes which are connected with the upper semiconductor layer,
 wherein a region at which the third electrode is in contact with the upper semiconductor layer has a different doping type from a region at which the fourth electrode is in contact with the upper semiconductor layer.   
     
     
         19 . The method of  claim 17 , wherein the first holes vertically overlap the germanium single crystal layer. 
     
     
         20 . The method of  claim 17 , wherein the silicon photonic crystal structure comprises the first holes and the second holes.