Berlin 2018 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 30: Heterostructures, interfaces, and surfaces
HL 30.3: Talk
Wednesday, March 14, 2018, 15:30–15:45, EW 202
Hole carrier profiles at the surface of p-type Ge measured by low-energy muon spin spectroscopy — •Thomas Prokscha1, Kim Chow2, Elvezio Morenzoni1, Zaher Salman1, Evelyn Stilp1,3, and Andreas Suter1 — 1LMU, Paul Scherrer Institut, 5232 Villigen, Switzerland — 2University of Alberta, Edmonton, T6G 2E1, Canada — 3Physics Institute, University of Zurich, 8057 Zurich, Switzerland
Macroscopic transport measurements and modelling are usually used to determine the charge carrier profiles across semiconductor interfaces. A local probe technique, capable of detecting the variation in carrier concentration, offers the unique possibility of measuring carrier profiles and manipulation directly without the need of model assumptions. Here we use for the first time the low-energy µ+ beam at PSI with tunable energies in the keV range to investigate charge carrier profiles and their manipulation by illumination in commercial p-type Ge wafers at varying mean implantation depths from 10 nm to 150 nm. In p-type Ge with doping levels of 1015 cm−3 and 1016 cm−3 we observed a depletion of holes in the top 150 nm and 50 nm, respectively. The depletion zone can be persistently removed by illumination with blue light due to filling of empty surface acceptor states with photo-generated electrons [1]. By illumination with red light the photo-generated electrons have not sufficient energy to overcome the surface barrier of about 1 eV [1], and a dynamic equilibrium concentration of holes is observed, which increases as a function of depth.
[1] T. Prokscha et al., Sci. Rep. 3, 2569 (2013).