Hall mobility enhancement caused by annealing of Si0.2Ge0.8/Si0.7Ge0.3/Si(001) p-type modulation-doped heterostructures

Abstract

The effect of post-growth furnace thermal annealing (FTA) on the Hall mobility and sheet carrier density measured at 9–300 K in the Si0.2Ge0.8/Si0.7Ge0.3/Si(001) p-type modulation-doped heterostructures was studied. FTA treatments in the temperature range of 600–900 °C for 30 min were performed on similar heterostructures but with two Si0.2Ge0.8 channel thicknesses. The annealing at 600 °C is seen to have a negligible effect on the Hall mobility as well as on the sheet carrier density. Increases in the annealing temperature resulted in pronounced successive increases of the mobility. For both samples the maximum Hall mobility was observed after FTA at 750 °C. Further increases of the annealing temperature resulted in a decrease in mobility. The sheet carrier density showed the opposite behavior with an increase in annealing temperature. The mechanism causing this behavior is discussed. Structural characterization of as-grown and annealed samples was done by cross-sectional transmission electron microscopy.

Hall mobility of narrow Si0.2Ge0.8–Si quantum wells on Si0.5Ge0.5 relaxed buffer substrates

“…The decrease became slightly steeper above ϳ60 K. For the 2.5-nm-thick QW sample, the mobility increases up to a temperature of 60 K. Figure 3 summarizes the mobility at 8 K as a function of QW thickness L. The highest of 0.44 m 2 /V s obtained for the 7-nm-thick sample at 8 K is larger than the recently reported value of 0.062 m 2 /V s for a 10-nm-thick Si 0.2 Ge 0.8 QW grown at 300°C on Si 0.8 Ge 0.3 virtual substrates. 9 The factor 7 higher mobility of our sample reflects the small roughness of the substrates and the small thickness fluctuation of our samples. When L is increased from 2.5 to 4.5 nm, increases steeply.…”

Scattering mechanisms in high-mobility strained Ge channels

“…A 4.2 K mobility of 87 000 cm 2 V Ϫ1 s Ϫ1 ͑at 6.2ϫ10 11 cm Ϫ2 ) has already been reported 1 and roomtemperature mobilities of around 3000 cm 2 V Ϫ1 s Ϫ1 have been found using mobility spectrum analysis. [1][2][3] Some of the physical properties of holes in strained Ge have been studied. 4 -7 Here, we analyze the sheet density dependence of the mobility in high-mobility material.…”

DC and low-frequency noise analysis for buried SiGe channel metamorphic PMOSFETs with high Ge content

“…As x −y = 0.3 in both structures the strain in the p-channel will be the same. The PMOSFET devices were fabricated using reduced thermal budget processing at 650 • C, to minimize Ge out-diffusion from the strained Si 1−x Ge x channel [7] and to avoid Sb penetration to the channel, with 200 nm of plasma enhanced CVD (PECVD) SiO 2 deposited as a field oxide. In the active transistor area the field oxide was removed by wet chemical etching.…”