CBE GROWTH OF 2-PERCENT-STRAINED INASP MQWS FOR 1.5 MU-M WAVELENGTH LASER-DIODES

Structural and optical properties of the compressively strained multip le quantum wells (MQWs), where InAsP well layer strain ranges from 1.9 -2.15%, have been studied. Transmission electron microscopy reveals th at 1.9%-strained MQWs have flat interfaces whereas 2.15%-strained MQWs have wavy interfaces as growth proceeds. The 1.9%-strained MQW photol uminescence (PL) intensities stay quite strong in the barrier tensile strain range of 0=0.4% but are reduced by 90% in the 0.6-0.9% range, i .e. strain compensation is not useful in the highly strained MQWs. a n ew type of MQW structure, where a thin compositional-graded InAsxP1-x layer is inserted between the well and the barrier layers, provides si x-well MQWs having high PL intensities. These results show that the sh earing stress at the well-barrier interface rather than net strain pla ys an important role in growing the 1.9%-strained MQWs. We have fabric ated the buried heterostructure MQW lasers emitting at a 1.5 mu m wave length light with a low threshold current of 6.5 mA and a large differ ential gain of 9.3 x 10(-16) cm(2). (C) 1998 Elsevier Science B.V. All rights reserved.