Hitoshi Shimizu, Kouji Kumada, Nobumitsu Yamanaka, Norihiro Iwai, Tomokazu Mukaihara, Akihiko Kasukawa
Work is under way on the development of Group III-V optical and electronic devices using gas-source molecular-beam epitaxy (GSMBE), an extension of molecular-beam epitaxy in which the Group V are gas-source (AsH3, PH3). High uniformity of composition and thickness has been achieved by optimizing the position and conditions of growth. In considering the application of GSMBE to 1.3µm MQW lasers, n-type modulation-doped MQW lasers using InAsP multi-quantum wells were studied, since GSMBE is suited to the doping of extremely restricted regions. Using a laser selectively n-doped to 1 x 1018cm-3 at optimized growth temperature, with a cavity length of 1200mm, the extremely low threshold current density Jth of 250 A/cm2 was achieved. This has for the first time confirmed the superiority of GSMBE for selective n-doping with respect to threshold current density.