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The shapes of micro-pits formed in an Al-Pd-Mn icosahedral quasicrystal have been examined by alternating sequence of electrochemical etching and scanning electron microscopy (SEM) observations. Anodic etching was executed on fivefold and twofold surfaces of the single-quasicrystal. Prolonged anodic etching in a solution of CH 3 OH + HNO 3 (volume ratio 3 : 1) followed by SEM observations has revealed that two different types of micro-pits, i.e. pre-existing micro-voids and electrochemical etch-pits, develop into the same regular shape. The micro-pits develop into a pentagonal pyramid on the fivefold surface, and a flat-bottomed rhombic pyramid on the twofold surface. It is shown that these two polyhedral etch-figures correspond to two different sections of a regular rhombic triacontahedron.

When (111) wafers of Te-doped GaP were etched in H 2 SO 4 + H 2 O 2 + H 2 O (5 : 1 : 1 in volume ratio) at a temperature above 70°C for a period longer than 3.6 x 10 3 s, abnormal etch pits of asymmetric shape formed on the (111) P surface in minor density compared to those of normal triangular pits and spiral pits. From microscopic observation, the abnormal pit had an etch beak projecting from its apex. In order to clarify the origin of abnormal etch pits, structural defects in the wafers were examined by transmission electron microscopy after thinning. As a result, they were classified into several types such as dislocations, dislocation loops, precipitates and lineage defects composed of a dislocation bundle. As the lineage defects often take such a peculiar configuration as a zigzag pattern, we suppose that the abnormal etch pit with a beak would nucleate owing to preferential dissolution along the lineage defect.

The technique of chemical polishing or electropolishing of n-GaP to obtain a flat (111) surface has not fully been developed. We examined the anodic etching behavior of the (111) surface of Te-doped GaP in aqueous KOH solution at room temperature under normal indoor illumination. The (111) surface became smooth microscopically by etching at a voltage above 24 V in 0.1-0.5 kmol/m 3 KOH. In addition, we have also demonstrated a novel method for revealing lattice defects in the crystal by anodic etching under specified conditions.

High rate deposition of Al (99.999% in purity) from dual sources of W-baskets was carried out onto NaCI crystals which were cleaved in air and heated at temperatures of 523 to 643 K in an ordinary high vacuum (2 x 10 -3 Pa). From a transmission electron microscopic observation, it was found that when deposited in thickness of 80 to 200 nm at a substrate temperature of 623 K the films grew continuously with island structure in (100) orientation. Moreover, (100) flat single-crystal films thicker than 200 nm often developed without containing islands and they usually included numerous dislocations. Most dislocations were come out from the films during heating to a high temperature above 873 K in the electron microscope.

An icosahedral Al 70 Pd 20 Mn 10 quasicrystal was etched under several etching conditions with solutions composed of HF and H2O plus HCl and/or HNO 3 . The formation of etch pits was examined closely by scanning electron microscopy and replica electron microscopy. When etched for 5 s at 293 K with the etchants of different compositions, the faceted pits were often observed except for a few exceptions. All those pits revealed the similar shape of pentagonal dodecahedron where the pentagonal faces were curved slightly near their corners and edges. By etching for 5 s with a solution of HF+HCl+H 2 O (1:3:5 in volume ratio), the average size of the pits decreased from 4.5 to 2.5 μm with an increase of etching temperature from 273 to 333 K, and the pentagonal faces tended to be flattened above 313 K. The pentagonal faces near the corners and edges of the pits became more curved and the average size remained unchanged (∼4.5 μm) with increasing etching time in the range of I and 20 s at a temperature of 293 K. By comparing the surfaces before and after etching at the same areas, it was concluded that the faceted pits originated from irregular small holes which pre-existed on the polished surface.

Simultaneous evaporation of Al (99.999% in purity) from dual sources of W baskets was carried out onto a surface of NaCl crystal cleaved in an ordinary high vacuum (10 -3 Pa), and the crystallinity of the deposited film was examined through a transmission electron microscope (TEM). The substrate temperature varied in the range from room temperature to 523 K during the preparation of Al films of thickness 100 nm. On the other hand, the deposition thickness was changed from 20 to 130 nm at a substrate temperature of 473 K. A continuous single-crystal film with the (111) plane of thickness more than 70 nm was obtained on a substrate heated to 473 K.

La dissolution de la surface (111) de monocristaux de cuivre a ete etudiee en fonction de la concentration en agent oxydant (NH 4 ) 2 S 2 O 8 et en agent complexant NH 4 OH dans la solution de Young (NH 4 ) 2 S 2 O 8 -NH 4 OH-NH 4 Br lors d'une attaque d'une duree de 10s a la temperature de 280K.