Interface Structure and Surface Polarity in CdTe/ZnTe/(112)Si Hetero-Epitaxial System
Abstract
Tellurium adsorption on clean (112) Si surfaces obey a second order kinetic law. The adsorbed Te ad-atoms are highly immobile. Activation energies of adsorption and desorption were measured by isothermal desorption rates. A surface bond energy model was used to calculate the total energy for Te chemisorption on (111) terraces. This model yields a Si-Te bond energy of about 3.46 eV. As-Te bond energy was found to be about 4.0 eV. ZnTe/CdTe epitaxy on As-passivated Si gave uniform and smooth surfaces. As-passivated surfaces always produced B-type CdTe crystallographic polarity. Te coverage on As-passivated surfaces were significantly lower than the coverage observed on clean Si surfaces. A ZnTe nucleation model is proposed suggesting an enhancement in Te surface mobility occurs on As-passivated surfaces. ZnTe nucleation on As-passivated surfaces initiates at the step edges. ZnTe/CdTe epitaxy on Te-terminated Si and directly on clean (112) Si produced rough surface morphology. The surface polarity type depended on the initial Si surface preparation. A B-type polarity is observed for surfaces treated with Te at temperatures above 500 deg C. For Te adsorption temperatures below 450 deg C, CdTe surfaces were A-type and heavily faceted. ZnTe growth on Te-terminated surfaces is suggested to initiate mainly from nucleating on the terraces.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1998
- Accession Number
- ADA400225
Entities
People
- N. K. Dhar
Organizations
- United States Army Research Laboratory