| 摘要 |
PROBLEM TO BE SOLVED: To provide a quantum cascade laser which operates at a low threshold current density, over a wide band range of levels. SOLUTION: As shown in Fig.1(A), the quantum cascade laser 100 is equipped with an InAs substrate 101, a Si-InAs clad layer 102 formed on the InAs substrate 101; a Si-InAs core layer 103 formed on the Si-InAs clad layer 102, an active region 110 formed on the Si-InAs core layer 103; a Si-InAs core layer 104 formed on the active region 110; and a Si-InAs core layer 105 formed on the Si-InAs core layer 104. The active region 110 consists of a cyclical repetition of a multiple quantum-well structure, wherein well layers and barrier layers are stacked alternately, as shown in Fig.1(B). InAs<SB>1-x</SB>Sb<SB>x</SB>(0≤x<1) is used for the well layers 111, while AlAs<SB>y</SB>Sb<SB>1-y</SB>(0≤y<1) is used for the barrier layers 112. The compositions of the well layers 111 and the barriers layers 112 are so selected as to reduce the strain in the active region 110. COPYRIGHT: (C)2009,JPO&INPIT
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