| 摘要 |
PROBLEM TO BE SOLVED: To reduce a necessary threshold current density for oscillating a laser, by providing on its substrate a low-temperature buffer layer to provide just thereon one of the growth layers including InGaN, AlInN and AlGaInN layers, and by making the lattice constant of the growth layer larger than the one of an active layer. SOLUTION: On a sapphire substrate 11 having (0001) plane and its principal plane, a GaN low-temperature buffer layer 12 is made to grow. Thereon, In0.08 Ga0.92 N buffer layer 13, an n-type Al0.1 Ga0.9 N clad layer 14, a GaN active layer 15 and a p-type Al0.1 Ga0.9 N clad layer 16 are made to grow successively. With respect to the interatomic distances in the crystalline planes of the respective layers, since the lattice constant of the (a) axis of the In0.08 Ga0.92 N buffer layer 13 is specified by 3.218Å, a tensile strain of about 0.9% is introduced into the GaN active layer 15 having 3,189Å as the lattice constant of its a-axis. Thereby, in the layer 15, CH band comes to have the highest valence band energy, and a laser comes to oscillate by the transition of electron between the CH band and conduction band, making its threshold current density reducible. |
