Frustrated incomplete donor ionization in ultra-low resistivity germanium films
- Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States)
- Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604 (United States)
The relationship between carrier concentration and donor atomic concentration has been determined in n-type Ge films doped with P. The samples were carefully engineered to minimize non-active dopant incorporation by using specially designed P(SiH{sub 3}){sub 3} and P(GeH{sub 3}){sub 3} hydride precursors. The in situ nature of the doping and the growth at low temperatures, facilitated by the Ge{sub 3}H{sub 8} and Ge{sub 4}H{sub 10} Ge sources, promote the creation of ultra-low resistivity films with flat doping profiles that help reduce the errors in the concentration measurements. The results show that Ge deviates strongly from the incomplete ionization expected when the donor atomic concentration exceeds N{sub d} = 10{sup 17} cm{sup −3}, at which the energy separation between the donor and Fermi levels ceases to be much larger than the thermal energy. Instead, essentially full ionization is seen even at the highest doping levels beyond the solubility limit of P in Ge. The results can be explained using a model developed for silicon by Altermatt and coworkers, provided the relevant model parameter is properly scaled. The findings confirm that donor solubility and/or defect formation, not incomplete ionization, are the major factors limiting the achievement of very high carrier concentrations in n-type Ge. The commercially viable chemistry approach applied here enables fabrication of supersaturated and fully ionized prototypes with potential for broad applications in group-IV semiconductor technologies.
- OSTI ID:
- 22395469
- Journal Information:
- Applied Physics Letters, Vol. 105, Issue 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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