Ultrathin Silicon/Germanium Microstructures

Si/Ge MIST - 7128

Work Area: Microelectronics

Keywords Si/Ge heterostructure system, Si/Ge quantum wells, SimGen strained layer superlattices, Si MBE, characterisation of heterostructures

Start Date: 1 July 92 / Duration: 36 months / Status: running

[ participants / contact ]

Abstract Si/Ge microstructures grown on <100>Si substrates offer the possibility of integrating optical devices (LED and photodiode) with Si-based conventional integrated circuits (ICs). These microstructures have a variety of multifunctional device capabilities (eg SiGe Gunn diode) making use of novel bandstructure effects and transport phenomena in strained Si/Ge heterostructures. Their properties are predicted and investigated with theoretical models and their structural and material properties measured using extensive characterisation techniques. Simple two-terminal devices (eg mesa and waveguide diodes) serve as demonstrators for the device performance capability.


The goal is to study the SiGe heterostructure system with special emphasis on atomically thin layers deposited on an Si substrate by MBE. The project aims to exploitat novel effects and material properties such as optical transitions in the near-infrared regime, strain effects, non-linear optical properties and change of carrier mobility. Simple demonstrator devices showing the performance and characteristics of Si-based optoelectronic devices are planned.

Approach and Methods

The work is divided into the following major tasks:

Progress and Results

Major achievements so far are:


In general, the Si/Ge microstructure system can serve as model system to study strain effects, mismatch accomodation and growth techniques for other strained heterostructure systems. The results obtained here for growth parameters, characterisation techniques and numerical tools for calculating the bandstructure of SiGe microstructures are of broad usage and can be applied in other heterostructure systems such as for example in the III-V material area (egInGaAs/GaAs) as well.

Latest Publications

Information Dissemination Activies

Conferences: NATO ARW, Riva Sept. 92; 21th ICPS Beijing, China, 8/92; Symposium "Si-based heterostructures", AVS Meeting, Chicago 11/92; Spring Meeting of MRS, Symposium "Si-based optoelectronic materials", San Francisco, 4/93; Modulated Semiconductor Structures , Garmisch-Partenkirchen, 8/93. Two symposia and conferences on related topics have been organised by partners of this research action :


Daimler-Benz AG (DB) - D
Research Center Ulm
Wilhelm-Runge Str. 11
D - 89081 Ulm


University of Newcastle (UNC) - UK
Technische Universität München (TUM) - D
Foundation of Research and Technology-Helas (FORTH) - GR

Associate Partners

University of Lund - S
Universität Linz - A


Dr. H. Presting
tel +49/731 505-2049
fax +49/731 505-4102

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Si/Ge MIST - 7128, August 1994

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html version of synopsis by Nick Cook