Characteristics of n-GaPx As1–x–pGa1–yAlyPxAs1–x heterojunction lasers emitting visible radiation

An investigation was made of the characteristics of single-sided n-GaP_x As_1–x–pGa_1–yAl_yP_xAs_1–x (x = 0.1–0.45) heterolasers grown by liquid epitaxy and emitting visible radiation. The lasers with x < 0.3 were found to have threshold current densities in the range j_t = 2–3 kA/cm² at 77°K and 15–20 kA/cm² at 300°K. The dependence of j_t on the photon energy was determined at 77 and 300°K. The output power of the lasers with x = 0.2–0.25 was 6–8 W per pulse (500 Hz repetition frequency, 0.1 (μsec duration) at 77°K and 2–2.2 W at 300°K. A considerable increase in j_t and a fall of the output power were observed in the range x > 0.3. The differential efficiency of the better lasers was 5–8 % at 300°K and 20–25 % at 77°K.