Infrared light emitting device

An infrared light emitting device comprising:

• a semiconductor substrate;
• a first layer formed on the semiconductor substrate and having a first conductivity type;
• a light emitting layer formed on the first layer;
• and
• a second layer formed on the light emitting layer and having a second conductivity type, wherein
• the first layer comprises, in the stated order:
• a layer containing Alx(1)Gap(1)In1−x(1)−p(1)Sb;
• a layer having a film thickness ty(1) in nanometers and containing Aly(1)Gaq(1)In1−y(1)−q(1)Sb;
• and a layer containing Alx(2)Gap(2)In1−x(2)−p(2)Sb,
• where ty(1), x(1), x(2), y(1), p(1), p(2), and q(1) satisfy the following relations:
• 0<ty(1)≤2360×(y(1)+q(1)−x(1)−p(1))−240(0.11≤y(1)+q(1)−x(1)−p(1)≤0.19),
• 0<ty(1)≤−1215×(y(1)+q(1)−x(1)−p(1))+427(0.19<y(1)+q(1)−x(1)−p(1)≤0.33),
• 0<ty(1)≤2360×(y(1)+q(1)−x(2)−p(2))240(0.11≤y(1)+q(1)−x(2)−p(2)≤0.19),
• 0<ty(1)≤−1215×(y(1)+q(1)−x(2)−p(2))+427(0.19<y(1)+q(1)−x(2)≤p(2)≤0.33),
• 0<x(1)+p(1)<0.18,
• 0<x(2)+p(2)<0.18, and
• 0<q(1)/(y(1)+q(1))≤1.