RESEARCH OF STACKED TWIN-ACTIVE LAYER GaInAsP/InP DYNAMIC SINGLE MODE LASERS

1)新型堆叠双有源层结构由两个激光区沿垂直方向堆叠组成，两个激光区通过隧道结相互连接。当我们将这种结构用于动态单模激光器时，在波纹表面的隧道结部分集成了光栅。2)首先，我们澄清了杂质掺杂条件，以获得简单GaInAsP/InP隧道结的低反向结电压，因为低电压是连接两个激光器所必需的。采用液相外延法将层厚控制在设计值，制备了GaInAsP/InP堆叠双有源层激光器，获得了通过隧道结连接两个有源层的生长条件。阈值电流密度平均为2.5kA/cm^2，与无有源层叠加的传统DH激光器相当。3)利用激光晶片制备了条纹宽度为3mum的脊波导激光器，获得了阈值电流为6OmA a，波长大于1.5mum。最后引入埋藏异质结构是必不可少的，因此我们尝试用质量输运法制造埋藏异质结构激光器。但经过高温退火处理后，隧道性能有所下降。从而证实了利用高阻半导体嵌入是嵌入这种多有源层结构的唯一方法。4)对叠加双有源层GaInAsP/InP动态单模激光器的激光波导进行了理论分析。给出了基横模工作的波导设计，并采用液相外延技术制备了激光器。生长后，在200 ~ 300a ^^ / kg范围内，光栅深度变浅。这是液相外延的一个特殊问题，因此为了避免这种光栅变形，需要使用分子束外延。阈值电流密度为3-4KA/cm^2.5)。通过对激光特性的研究，明确了对于堆叠双有源层激光器，上下有源层厚度相等是重要的。利用气源分子束外延可以生长GaInAsP化合物，具有高厚度可控性，因此提出了气源分子束外延。获得了GaInP等磷化物的基本生长条件。少

1)The novel stacked twin-active layer structure consisted of two laser regions stacked along the vertical direction, which are connected each other through tunnel junction. When we use this structure for dynamic single mode lasers, a grating is integrated in the tunnel junction part corrugating the surface.2)First, we clarified the impurity doping condition to get a low reverse junction voltage for simple GaInAsP/InP tunnel junctions because the low voltage was essential for connecting two lasers. GaInAsP/InP stacked twin-active layer lasers were fabricated by a liquid phase epitaxy controlling the layer thicknesses in designed values, and the growth condition to connect two active layers by the tunnel junction was obtained. The threshold current density was 2.5kA/cm^2 in average, which was comparable with conventional DH lasers without active layer stack.3)Using the Laser wafer, ridge-waveguide lasers with the stripe width of 3mum were fabricated to get the threshold current of 6OmA a … More t 1.5mum in wavelength. Eventually introducing buried heterostructure is essential, so we tried the use of mass- transportation method to fabricate the buried heterostructure laser. But the degradation of tunneling property was observed after the high temperature annealing process. Thus it was confirmed that the embedding by use of high resistive semiconductors was the only method to embed such a multiple active layers structure.4)The laser waveguide of the stacked twin-active layer GaInAsP/InP dynamic single mode laser was analyzed theoretically. The waveguide design for the fundamental transverse mode operation was given and the laser was fabricated by liquid phase epitaxy. After the growth, the depth of grating became shallow in 200-300A^^ﾟ. This is a specific problem for liquid phase epitaxy, so to avert such a grating deformation the use of molecular beam epitaxy is needed. The threshold current density was 3-4KA/cm^2.5)Through the investigation of lasing properties, it was clarified that for the stacked twin-active layer laser, to equate the thickness of upper and lower active layers was important. So the gas-source molecular beam epitaxy (MBE) with a high thickness controllability, was introduced because GaInAsP compounds could be grown though using MBE. The fundamental growth condition of phosphide compounds such as GaInP and so on was obtained. Less