Quantum cascade laser and method for making same

Abstract

The invention concerns a quantum cascade laser, comprising a substrate, a stack of layers, having a prismatic shape with substantially trapezoidal cross-section, comprising a lower surface arranged on the substrate, an upper surface and lateral surfaces, said stack forming a gain region and two walls between which the region is interposed, two electrodes arranged on either side of the stack, one of which is formed by an electrically conductive material layer covering at least partially the surface of the stack opposite the substrate, and an electrically insulating layer interposed between the two electrodes. The invention is characterised in that the electrically insulating layer completely covers the lateral surfaces of the prism, without overlapping on the upper surface, and its thickness is equal to at least a third of the stack thickness.

We claim:  
     
         1 . Process for manufacturing a laser, characterized in that it comprises the following operations: 
 deposition of layers designed to form said stack ( 12 );    deposition of a masking layer ( 14 );    etching of the masking layer ( 14 ) outside of the zone designed to form said stack;    etching of the layers designed to form the stack ( 12 ) outside of the masked zone;    metal organic chemical vapour deposition (MOCVD) of an electrically insulating layer ( 22 ) on the non-masked parts, until a thickness substantially equal to the thickness of the stack ( 12 ) is reached;    removal of the masking layer ( 14 ), and    deposition of a conducting layer ( 24 ), covering in particular the stack ( 12 ) on its upper surface.    
     
     
         2 . Process according to  claim 1 , characterized in that the operation of deposition of the electrically insulating layer ( 22 ) is performed until a thickness substantially equal to the thickness of the stack ( 12 ) is reached.  
     
     
         3 . Process according to  claim 1 , characterized in that said masking layer ( 14 ) is manufactured in SiO 2 .  
     
     
         4 . Process according to  claim 2 , characterized in that said masking layer ( 14 ) is manufactured in SiO 2 .