Electronic properties of doped glow-discharge amorphous germanium

• Published in: Solar energy materials 1982-01, Vol.8 (1), p.319-330
• Main Authors: Hauschildt, D., Stutzmann, M., Stuke, J., Dersch, H.
• Format: Article
• Language: English
• ISSN: 0165-1633
• DOI: 10.1016/0165-1633(82)90075-2

For glow-discharge a-Ge: H doped with phosphorus and boron the temperature dependence of conductivity and thermoelectric power has been investigated. For both dopants a maximum shift of the Fermi energy E F to the mobility edges of about 0.3 eV is obtained. The difference of the conductivity and thermoelectric power activation energies E Q = E δ - E s lies around 0.16 eV and varies only little with doping; it rises somewhat by hydrogen effusion at temperatures above 300°C. The spin density of undoped a-Ge: H is approximately two orders of magnitude larger than for a-Si: H ;it increases by irradiation with 3 MeV electrons and by hydrogen effusion by a factor of 4–5. Annealing at temperatures above 300°C leads to a positive sign of the thermoelectric power indicating that defect states created by hydrogen effusion pull the Fermi level below midgap.