Douglas Jayne

An x‐ray photoelectron spectroscopy study of AuxIny alloys

Four gold–indium alloys have been studied by x‐ray photoelectron spectroscopy. The binding energies and intensity ratios of the Au 4f7/2 and In 3d5/2 core levels were determined for the bulk alloy compositions of Au(10% In), Au3In, AuIn, and AuIn2. These values were determined for the native oxides on the materials, for the surfaces prepared by ion bombardment to remove the oxide and for surfaces scraped in situ with a ceramic tool to expose the bulk composition. These results furnish calibration values that allow determination of the composition of thin films of this alloy system. In addition the binding energies add to the data base for understanding the effect of alloying on core level binding energies. As an illustration, these results are used to determine the composition of a series of alloy films formed by incongruent evaporation of an alloy charge.

Core level x‐ray photoelectron spectroscopy of AuxGay alloys

Five Au–Ga alloys have been studied using x‐ray photoelectron spectroscopy as part of the program to determine alloy effects on core level binding energies and identify thin film and bulk compositions of unknown AuxGay alloys. The binding energies and peak intensities of the Au 4f, Ga 2p3/2, Ga 3p3/2, and Ga LMM core levels were determined for pure Au and Ga along with bulk alloy compositions of α‐Au0.88Ga0.12, β‐Au0.78Ga0.22, γ‐Au9Ga4, AuGa, and AuGa2. These values were determined for surfaces scraped in situ to expose the bulk composition. The Au 4f7/2 binding energies were 83.95 eV for pure Au and 84.4, 84.6, 84.9, 85.2, and 85.5 eV for each of the respective alloys, while the Ga core levels and Auger energy shifted less than 0.3 eV over the range of alloy compositions. These results exhibit the same trend as the previously studied Au–In system and furnish calibration values that allow determination of the composition of unknown alloys.

An innovative method for preparing semiconductor charges used in crystal growth and shear cell diffusion experiments

An innovative technique for machining semiconductors has been developed. This technique was used to prepare semiconductor charges for crystal growth and shear cell diffusion experiments. The technique allows brittle semiconductor materials to be quickly and accurately machined. Lightly doping the semiconductor material increases the conductivity enough to allow the material to be shaped by an electrical discharge machine (EDM).

Closed-ampoule diffusion of sulfur into Cd-doped InP substrates - Dependence of S profiles on diffusion temperature and time

In order to optimize the fabrication of n+–p InP solar cells made by closed‐ampoule diffusion of sulfur into p‐InP:Cd substrates, we have investigated the influence of diffusion conditions on sulfur diffusion profiles. We show that S diffusion in InP is dominated by the P vacancy mechanism and is not characterized by a complementary error function as expected for an infinite source diffusion. The S diffusion mechanism in p‐InP is qualitatively explained by examining the depth profiles of S, P, and In in the emitter layer and by taking into account the presence and composition of different compounds found to form in the In–P–S–O–Cd system as a result of diffusion.

XPS, Auger And SEM Analysis Of The InP Surface After Closed-Ampoule Diffusion With Sulphur At Several Diffusion Temperatures

In an attempt to identify the factors which limit the performance of InP solar cells made by the closed-ampoule diffusion of sulphur into p-type InP substrates, and in order to optimize the fabrication process, we have done a detailed analysis of the InP surface and of the diffused emitter region using XPS, Auger, SEM and EDAX for diffusion temperatures of 600, 625, 650, 675, 700 and 725°C for a fixed diffusion time of 3 hours, and diffusion times of 1, 2, 3, and 4 hours for a fixed temperature of 675°C. In this paper, we present the results of this analysis, showing how the morphology and chemical composition of the InP surface layer changes with the diffusion temperature and identifying the possible mechanisms which limit the photocurrent and the open circuit voltage of solar cells fabricated using the closed-ampoule diffusion process.