For the growth of many high-quality photonic devices, especially surface emission lasers with a vertical resonance
cavity (Vertical External Cavity Surface Emitting Laser, VECSEL) very important is to know the actual concentration of
the carriers in each layer laser structure resulting from the presence of unintentional impurities. Studies of doping profile
of this type multilayer structure can be carried out only by comparing the measured capacitance - voltage characteristics
with the calculated theoretically. The paper presents results of research VECSEL structures with different numbers of
quantum wells 4, 8, 12, 16, produced by molecular beam epitaxy. Measurements of the capacitance - voltage
characteristics has been performed using mercury probe in the system for automatic measurement of C-V, I-V, G–V. The
results of C-V measurements and numerical simulations have confirmed the possibility to control the level of
unintentional impurities in the different layers of the laser VECSEL structure. The lowest concentrations of unintentional
impurities were obtained for structures with highest power output.
Effect of stress related to presence of surface insulation layer (silicon nitride and oxide films deposited on silicon surface) on carrier concentration in Czochralski grown silicon (Cz-Si) annealed at 450 - 600 degree(s)C for up to 50 hours were investigated. The SiO2 film of about 120 nm thickness exerted tensile ((sigma) approximately equals 3.5(DOT)108 Pa) and the Si3N4 of about 290 nm thickness compressive ((sigma) approximately equals 3.5(DOT)108 Pa) stress on the Si matrix. The difference in electron concentration (Delta) N, was detected in the samples with Si3N4 layers after annealing at 450/600 degree(s)C in comparison to that in the samples subjected to the same treatment but without insulation film. The (Delta) N value was dependent on the initial oxygen concentration, type of conductivity and thermal history of the samples. The observed effect was analyzed accounting for the doping redistribution in the surface layer of Cz-Si during films growth. This effect can be explained in part by assuming that the rate of thermal donor generation is enlarged under compressive stress as is in the case of hydrostatic stress produced by ambient argon atmosphere during annealing. The difference in electron concentration (Delta) N, detected in the samples with SiO2 layers after annealing at 450/600 degree(s)C, was much less pronounced in comparison to the Si3N4 layers and even less than for samples without insulation layer. This effect can be explained in part by assuming that the rate of thermal donor generation is reduced under tensile stress.
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