W e report the investigation of impurity-induced disordering (110) in strained In,Ga, -,As/GaAs ( x = 0.21-0.24) single quantum well (ow) heterostructures using a two-stage Zn diffusion and thermal annealing process. The samples were grown by MOVPE, and different shallow Zn diffusion depths were allowed in the GaAs cap layer in order to vary the Zn concentration in t h e ow. Thermal annealing of the samples at 785 "C for 10 min under an AsHJH, atmosphere then created 110. Both partially disordered and completely disordered ow heterostructures were studied. The In-Ga interdiffusion was monitored by the photoluminescence (PL) spectroscopy of the ground state emission from the aw. The interdiffusion coefficients were determined by adjusting t h e data calculated by using the envelope function approximation with the shifts of the PL peak position after the annealing. T h e interdiffusion coefficient is found to be very strongly dependent on the Zn diffusion depth, and consequently on the Zn concentration in t h e ow layer, Finally, we propose a model that involves an interstitial migration process in order to explain t h e enhancement of In-Ga interdiffusion by Zn diffusion '

We have studied the effect of Zr addition on the field dependence of transport J c for filamentary (Nd Eu Gd)Ba 2 Cu 3 O x superconductors to enhance the flux pinning. We prepared the filamentary (Nd 0 33 Eu 0 38 Gd 0 28 )Ba 2 Cu 3 O x Zr y (y = 0, 0.001, 0.002) precursors by a solution spinning method. The precursor was partially melted in flowing 0 1%O 2 + Ar under various heating conditions to obtain high J c value. The optimum heating condition was dependent on sample diameter. A maximum J c value of 3 10 4 A cm 2 at 77 K and self-field was attained for the sample with 0.001 at% Zr. The samples had well aligned texture along the filament diameter as well as the length. The J c was measured at 77 K in applied magnetic fields up to 14 T by rotating the sample along the direction perpendicular to the filament length. Anisotropic behavior of the field dependence of J c was detected. Although the J c values measured at the optimum angle for the samples with 0.001 at% Zr decreased with increasing the applied fields above 10 T, the J c values for the Zr addition samples were higher than that for the non addition sample by applying the fields up to 11 T.

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We have investigated the correlation between contact resistance, heat treatment, and micro structure in ohmic contacts on n-InP. The samples consisted of three different structures: 50 nm-Ni/200 nm-AuGe/n-InP, Au/100 nm-Pt/100 nm-Ti/50 nm-Ni/n-InP, and 200 nm-Au/100 nm-Pt/100 nm-Ti/ 50 nm-Ni/200 nm-AuGe/n-InP. After annealing the samples, depth profiles obtained by Auger electron spectroscopy and ion sputtering showed a tendency of the Ge to migrate from the Au-Ge alloy towards the Ni layer, as well as an accumulation of Ni at the semiconductor interface. A Ni-P phase is identified as being responsible for the ohmic character of the metal/InP interface. Specific contact resistivities were measured for the three different types of metallizations. We observed that the resistivity is sensitive to the annealing temperature and related to the amount of Ni at the metal/InP interface. The use of overlayers is suggested to avoid migration of the semiconductor components towards the contact surface.

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