AVS 51st International Symposium
    Electronic Materials and Processing Monday Sessions
       Session EM-MoP

Paper EM-MoP10
On the Surface Morphology of CdTe Thin Films Evaporated onto Rotating Substrates

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: G.G. Rusu, Al.I. Cuza University, Romania
Authors: G.G. Rusu, Al.I. Cuza University, Romania
M. Rusu, Al.I. Cuza University, Romania
Correspondent: Click to Email
CdTe thin films were prepared by thermal evaporation under vacuum by quasi-closed volume technique onto unheated glass substrates. During the evaporation process, the substrates holder were periodically passed (by rotational moving) over the evaporating source. As result of step by step deposition, multi-layered films were obtained. Depending on the rotating speed (varied between 20 and 210 rpm) and source temperature the thickness of the individual layers ranged from 0.75 nm to 7.60 nm. The total film thickness, ranged between 320 and 510 nm. For samples deposited in various conditions, AFM investigations were performed and the average roughness (a-r) and the root mean square surface (rms) roughness were calculated. The obtained results revealed a strong dependence of film surface morphology on the source temperature and rotational speed. At lower temperature source (925 K), the surface roughness decreases (from 2.30 to 0.57 nm) with increase of rotational speed, v, while at greater source temperature (1165 K) the surface roughness increase (from 0.50 to 2.10 nm) with v. Also, at greater source temperature, the films present a tellurium excess. The heat treatment of the films determines the increase of surface roughness and the precipitation of tellurium excess as nanocrystallites embedded in CdTe films.