Study of doping of Ge0.96 Si0.04:H films with B, and P during low frequency plasma deposition at low temperature

The films studied were grown at the temperature T<inf>d</inf>= 160 °C and doped by boron (B) and phosphorus (P) by incorporation of diborane (B<inf>2</inf>H<inf>6</inf>) and phosphine (PH<inf>3</inf>), respectively, in gas mixture used for the deposition. For B-doped films changing boron concentration in gas phase C<inf>B</inf>^gas from 0.04% to 0.06%, resulted in changing electrical characteristics: conductivity activation energy E<inf>a</inf> and room-temperature conductivity σ<inf>RT</inf> from E<inf>a</inf>=0.32 to 0.52 eV and σ<inf>RT</inf>=10^𢄤4 to 10⁻⁷ Ω⁻¹ cm⁻¹, respectively, suggesting compensation of electronic conductivity of the films. Further increasing C<inf>B</inf>^gas from 0.06% to 0.14% caused a reduction of E<inf>a</inf> from 0.52 to 0.31 eV and increasing of σ<inf>RT</inf> from 10⁻⁷ to 10⁻⁴ Ω⁻¹ cm⁻¹. Similar behavior of electrical properties with boron incorporation has been reported in the B-doped Ge:H films deposited at T<inf>d</inf>=300°C in [1]. The P-doped films show continuous change in activation energy ranging from E<inf>a</inf>=0.32 to 0.18 eV and room temperature conductivity ranging from σ<inf>RT</inf>=2.3×10⁻⁴ to 1.8×10⁻² Ω⁻¹ cm⁻¹ with P incorporation. Thus effective B- and P-doping of Ge-Si films deposited at T<inf>d</inf>=160 °C has been demonstrated.