Donald F. Weirauch

Correlation of the anisotropic etching of single−crystal silicon spheres and wafers

Studies of the anisotropic etching of silicon single−crystal wafers and spheres were conducted using 10−M potassium hydroxide as the etchant. The etch rates along the major slow−etch directions were measured. The sides of circular mesas etched into (111), (110), and (100) wafers were found to be inclined to the wafer surface. The angles of inclination varied with azimuthal position and could be correlated with the slow−etch directions measured from an etched sphere. A method was developed to predict these angles of inclination for surfaces of varied orientation using the rate of etching data and angular measurements from an etched sphere.

Inhomogeneity model for anomalous Hall effects in n‐type Hg0.8Cd0.2Te liquid‐phase‐epitaxy films

Anomalous Hall effects, i.e., peaks in the temperature dependence of the Hall coefficient and Hall mobility, have been observed in liquid‐phase‐epitaxy (LPE) Hg0.8 Cd0.2Te films. After establishing that surface effects are not the cause of the anomalies and that our LPE films are indeed n type, we propose an inhomogeneity model with a network of extended p‐type inclusions in an n‐type matrix. Good fits to the experimental data have been obtained by computer simulation based on this model.

Terracing in HgCdTe LPE films grown from Te solution

Abstract Terracing in HgCdTe films grown by LPE from Te solution is influenced by many factors. These include melt-back of the substrate, substrate holder design, rotation rate of the substrate, thermal gradients, and growth rates. Many of the variables which influence terracing are interdependent and can be related to their effects on the supersaturation. Variables which tend to level the solute and/or thermal fields would tend to reduce terracing.

The hydrothermal growth of Al2O3 in HCl solutions

Abstract In agreement with thermodynamic predictions, the extent of reaction between Al 2 O 3 and HCl solutions was found to decrease with increasing temperature in the range of 300–550°C at 1700 bar pressure. The hydrothermal growth of sapphire (Al 2 O 3 ) and ruby (Cr doped Al 2 O 3 ) was achieved in HCl solutions.