Low-pressure MOVPE growth and characterization of strained-layer InGaAs-InGaAsP quantum well lasers

Abstract

High-quality strained-layer In x Ga 1- x As-InP quantum well structures, as revealed by photoluminescence and transmission electron microscopy studies, were grown by low-pressure metalorganic vapour phase epitaxy (MOVPE). Laser diodes at 1.5 μm wavelength employing compressively as well as tensile strained In x Ga 1- x As-InGaAsP quantum wells with better performance than the much more extensively studied bulk InGaAsP and unstrained quantum well lasers are demonstrated. Threshold current densities as low as 92 and 147 A/cm 2 were measured from tensile and compressively strained single quantum well lasers. For both signs of the strain, 0.8 mA threshold current operation is achieved of all-MOVPE grown semi-insulating planar buried heterostructure (SIPBH) lasers. These data represent, to the best of our knowledge, the lowest values reported so far for 1.5 μm wavelength lasers grown by any technique. Compressively strained multiple quantum well (MQW) lasers are found to excel in high power operation, as demonstrated by the record CW output power of 325 mW, resulting from improved threshold current, temperature sensitivity of the threshold current and external differential efficiency. The tensile strained MQW lasers show very high differential and total gain, resulting in very high operating temperature up to 140°C. Three-section distributed feedback lasers employing a compressively strained InGaAs MQW active region showed very large wavelength tuning ranges as high as 7.2 nm with a minimum linewidth as low as 700 kHz.