掺硅的砷化镓体晶体的若干特性

近年来,对砷化镓光电器件的研究结果表明,用作衬底的砷化镓晶体,以掺Si材料为佳.与掺Te和掺Sn的相比,它的发光输出量大,晶体完整性较好,因而受到广泛的重视.目前对掺Si晶体的研究,在研制无位错单晶生长的同时,对晶体的性质和微结构也进行了不少的工作^1-4].但对掺Si后的晶体中,由于杂质及缺陷的相互作用而引起晶体特性的变化,尚未见有系统的报道.

SOME CHARACTERISTICS OF Si-DOPED GaAs BULK CRYSTALS

In this paper, a study has been made of the compensation ratio (θ), the minority carrier diffusion length (L_p) and the dislocation density of Si-doped GaAs crystals grown by the horizontal Bridgman method. The study on compensation ratio shows that tie donor can be self-compensated through a defect equilibrium due to the formation of the Si_GaV_Ga complex, when the carrier concentration is greater than 10¹⁷cm^-3. Some relationships between L_p, dislocation density and θhave been found. The L_p decreases with the θ increasing and changes abruptly at around θ=0.3, while the θ found for dislocation-free and low dislocated crystals is greater than 0.38 with the carrier concentration in the range of 1~2×10¹⁸cm^-3. It may be suggested that the L_p and dislocation density are related to Si_GaV_Ga in some way, which is formed through the interaction between Si_Ga and V_Ga, and with V_Ga created in turn from Si and O, by the removal of Si from Ga sites.In general, the θ could be used as a satisfactory guide to the quality of Si-doped GaAs crystals.