Te Atomic Layer Research Articles

Observation of ALE growth process of ZnTe by RHEED.

The ALE growth process of ZnTe is investigated with RHEED intensity observation. It is found that when the substrate temperature is sufficiently low, physisorbed Zn and Te adatoms are present on the Zn and Te-coverd surfaces, respectively. The ZnTe layers not less than monolayer grow during one cycle of ALE by the presence of these excess adatoms. Evaporation of the surface atoms occurs during growth suspension. First, the excess adatoms desorb, and then Zn and Te atomic layers sublime with different sublimation time constants. At high temperatures, the layer-by-layer evaporation occurs, as is verified by RHEED intensity oscillation during the sublimation process.

Status of photon counting using solid scintillators (plenary lecture): R.L. Heath, Idaho National Engineering Laboratory Idaho Falls, Idaho, U.S.A. 83415

A superstructure of the rocksalt-type observed in quenched CVT-grown single crystals of Ge3.25(7)Sn1.10(3)Sb1.10(3)Te6 was elucidated by X-ray diffraction using fourfold twinned crystals (space group P3¯m1, a=4.280(1) Å, c=20.966(3) Å). The structure is built up of distorted rocksalt-type building blocks typical for long-range ordered GST materials and substitution variants thereof. In contrast to those phases, an exclusive ABC-type cubic stacking sequence of the Te-atom layers is present. High-resolution electron microscopy reveals spheroidal domains with this structure (average diameter 25 nm) whose stacking direction is perpendicular to the 〈1 1 1〉 directions of the basic rocksalt-type structure. Additional slab-like domains with a lateral extension up to 1 µm occasionally result in a hierarchical structure motif. Due to the similar electron counts of the elements involved, resonant diffraction was used in order to elucidate the element distribution in rocksalt-type building blocks of the stable layered compound 39R-Ge3SnSb2Te7 (R3¯m, a=4.24990(4) Å, c=73.4677(9) Å). Sb tends to occupy the atom site close to the van der Waals gaps while Ge concentrates in the center of the building blocks.

Oxidation of ZnSe (110) and ZnTe (110)

An oxidation model for ZnSe(110) and ZnTe(110) exposed to non-excited molecular oxygen has been proposed based on studies using the techniques of 21 eV photo-emission spectroscopy, contact-potential difference, and Auger electron spectroscopy. The model suggests that Se atoms in the top layer are substituted by O atoms in ZnSe. The substitution of Te by O also occurs but it is not limited to the top layer of Te atoms for ZnTe. Adsorption of oxygen inducing pinning of the surface Fermi level was observed.