shape of a tetrahedron truncated by a (100) plane. Observed cross sections corresponded in detail and with good precision to those
predicted by the model. SEM and TEM showed that cross sections were trapezoidal and triangular, respectively, in the two cleavage
planes of the wafer, and TEM showed that they were rectangular parallel to the surface plane, as predicted. Aspect ratios and angles
calculated from observed cross sections were in good agreement with predicted values. The pore patterns observed were also in good
agreement with those predicted and SEM observations of the surface further confirmed details of the model.