ALGAINP VISIBLE LASER-DIODES GROWN ON MISORIENTED SUBSTRATES

This paper provides a detailed description of (Al(x)Ga1-x)0.5In0.5P epitaxial layers, and the basic characteristics of AlGaInP laser diodes grown on misoriented substrates by metalorganic chemical-vapor deposition (MOCVD) with the objective of shortening the oscillating wavelength of AlGaInP laser diodes. Using (100) GaAs substrates with a misorientation of 5-7-degrees towards the [011] direction, the bandgap energy of (Al(x)Ga1-x)0.5In0.5P (x = 0, 0.5) epitaxial layers was about 50-60 meV wider than that for (100) substrates. A p-carrier concentration was obtained which was twice that of (100) substrates (p approximately 8 x 10(17) cm-3). The transverse-mode stabilized laser diodes oscillating at 655-657 nm were obtained without adding Al to the active layer. The maximum continuous-wave (CW) light output power was 25 mW. The maximum CW operation temperature (T(max)) and characteristic temperature (T0) were 85-degrees-C and approximately 100 K, respectively. The value was as high as those values for laser diodes oscillating in the 670-680 nm band. The laser diodes have been operating reliably for more than 3000 h under 3 mW at 50-degrees-C. By adding an Al composition of X = 0.15 to the active layer and using a 7-degrees misoriented substrate, the shortest room-temperature CW operation wave-length of 631 nm was obtained. The threshold current was 90 mA at 25-degrees-C and T(max) was obtained up to 40-degrees-C.