GaAs/GaAlAs heterostructure laser diodes grown by liguid phase epitaxy (LPE)

Abstract

A series of experimental study on the liquid phase epitaxy (LPE) growth of GaAs-GaAlAs laser diodes and their characteristics was carried out. Combined techniques of two-phase solution and supercooling were applied to fabricate laser diodes with very thin active layers and thin waveguide layers by using novel design of a graphite boat with lateral sliding. The double heterostructure, the four-layer heterostructure and the separate-confinement heterosturcture of laser diodes were fabricated and characterized. The single-quantum-well separate-confinement heterostructure (SQW-SCH) lasers with 300 Å GaAs active layer could be grown by this proposed technique at the typical growth temperature of 795℃. The characteristics of these single quantum well lasers showed the quantum size effect, such as the broadening spectrum of spontaneous emission in phololuminescence and electroluminescence, and the blue shift of lasing spectrum when increasing the bias current. The threshold current density of these single-quantum-well laser with broad-area structure was 500 A/cm² for cavity length of 600 µm. The output power of more than 400 mW/facet under pulsed condition was observed. The external quantum efficiency of 65% was obtained from SQW-SCH laser with cavity length of 450 µm having 25 µm-wide SiO₂ stripe-geometry structure.