Title :
Comparison of structural, optical and electrical properties of pyrite (FeS2) layers prepared by MOCVD (normal and low pressure) and reactive magnetron sputtering
Author :
Ellmer, K. ; Lichtenberger, D. ; Ennaoui, A. ; Höpfner, C. ; Fiechter, S. ; Tributsch, H.
Author_Institution :
Hahn-Meitner-Inst., Berlin, Germany
Abstract :
A comparative study of undoped pyrite layers prepared by reactive magnetron sputtering (RMS), low pressure (LP) and normal pressure (NP) MOCVD has been undertaken for the first time. Stoichiometric pyrite films can be grown by all three methods but at different temperatures. For RMS where the sulphur partial pressure is low (⩽10-2 mbar) the growth temperature is limited to values below 200°C. For MOCVD with partial pressures of the sulphur component between 2 mbar (LP) and 500 mbar (NP) pyrite could be prepared up to substrate temperatures of 600°C. All films show p-type conductivity. The temperature dependent conductivity of MOCVD pyrite films can be fitted by an exp(-AT-1/4)-law which indicates a variable range hopping mechanism. The sputtered films show a degenerated semiconductor behaviour (very weak temperature dependence). Only on the sputtered films Hall mobilities up to 25 cm2/Vs could be measured. Caused by the Burstein-Moss shift the bandgap of sputtered films is shifted from 1.0 eV to 1.5 eV
Keywords :
Hall effect; carrier mobility; chemical vapour deposition; electronic conduction in crystalline semiconductor thin films; energy gap; hopping conduction; iron compounds; optical constants; semiconductor growth; semiconductor materials; sputter deposition; stoichiometry; 10-2 to 500 mbar; 600 to 200 C; Burstein-Moss shift; FeS2; Hall mobilities; MOCVD; bandgap; degenerate semiconductor behaviour; electrical properties; growth temperature; low pressure; normal pressure; optical properties; p-type conductivity; partial pressures; pyrite; reactive magnetron sputtering; stoichiometric pyrite films; structural properties; temperature dependent conductivity; undoped pyrite layers; variable range hopping mechanism; weak temperature dependence; Conductive films; Conductivity; Hall effect; MOCVD; Optical films; Semiconductor films; Sputtering; Substrates; Temperature dependence; Temperature distribution;
Conference_Titel :
Photovoltaic Specialists Conference, 1993., Conference Record of the Twenty Third IEEE
Conference_Location :
Louisville, KY
Print_ISBN :
0-7803-1220-1
DOI :
10.1109/PVSC.1993.347038
