Studies on electronical properties of defects in silicon and gallium arsenide

[abstract missing

Spectroscopic observation of the TDD0 in silicon

The electronic transitions of 16 neutral thermal double donors (TDD1-TDD16) and of nine positively charged species (TDD1-TDD9) were observed previously in infrared absorption spectra. An earlier species (TDD0) was detected, however, only in persistent photoconductivity and Hall effect studies. In the present work, lines related to the electronic transitions from the ground to excited states in both neutral and singly ionized charge states of the TDD0 have been identified by infrared absorption and bistability of the defect has been confirmed. (C) 2003 Elsevier B.V. All rights reserved

Carbon-oxygen-related complexes in irradiated and heat-treated silicon: IR absorption studies

Carbon-oxygen-related complexes in Si crystals enriched with either oxygen (O-16,O-18) or carbon (C-12, C-13) isotopes were investigated by Fourier Transform infrared absorption spectroscopy. The samples were irradiated with electrons at room temperature as well as at elevated temperatures (400-600 degreesC). The oxygen isotopic shifts of the local vibrational modes related to C3 and C4 centers were determined. Several new lines were found to appear after irradiation at elevated temperatures. Possible assignments of them are suggested

Photocurrent spectroscopy on self-assembled InAs quantum dots embedded in InP

In this work, we report on an overview of recent results from Fourier transform photocurrent (FTPC) measurements in the infrared spectral region on ensembles of self-assembled InAs quantum dots embedded in a matrix of InP. In interband PC, clear signals related to the dots are observed. Comparing the PC- and PL spectra, we observe that the fundamental transition is absent in the PC spectra, which we interpret in terms of Pauliblocking due to a filled electron ground state of the dots. Our results furthermore suggest that an Auger process is involved in forming the interband PC signal. In intersubband PC, peaks related to transitions from the dots' ground- and first excited states to the conduction band of the matrix are observed. Using a novel approach of combining FTPC with illumination from an additional external nonmodulated light source, we have measured the spectral distribution of photoionization of excitons in quantum dots and found an exciton binding energy in good agreement with theoretical calculations

Interband transitions in InAs quantum dots in InP studied by photoconductivity and photoluminescence techniques

We report on a detailed investigation of the interband optics of self-assembled InAs dots embedded in a matrix of InP. In photoconductivity (PC) measurements, we observe optical processes related to the dots and a wetting layer, band-to-band excitation of the InP barrier, as well as to an interesting As-related impurity. In particular, the PC measurements reveal the electronic structure of the dots and strongly suggest that an Auger effect is involved in forming the PC signal. Comparing the PC and photoluminescence (PL) signals, we observe that the fundamental transition is not observed in PC, which we interpret in terms of Pauli blocking due to electrons populating the ground state of the dots. In general, it is demonstrated that the PC technique is in many respects complementary to PL and gives additional insight into the electronic structure of quantum dots. (C) 2004 American Institute of Physics

Intersubband photoconductivity of self-assembled InAs quantum dots embedded in InP

In this article, we present the results from photoconductivity measurements in the infrared spectral region (3-10 mum) on ensembles of self-assembled InAs quantum dots embedded in a matrix of InP. In the spectral distribution of the photocurrent, peaks are observed which we interpret in terms of transitions from the dots' ground- and first-excited states to the conduction band of the dots/matrix. Furthermore, we have calculated the expected photoresponse and found it to be in qualitative agreement with our experimental data

Defect engineering in Czochralski silicon by electron irradiation at different temperatures

Infrared absorption studies of defect formation in Czochralski silicon irradiated with fast electrons in a wide range of temperatures (80-900 K) have been performed. The samples with different contents of oxygen (O-16, O-18) and carbon (C-12, C-13) isotopes were investigated, The main defect reactions are found to depend strongly on irradiation temperature and dose, as well as on impurity content and pre-history of the samples. Some new radiation-induced defects are revealed after irradiation at elevated temperatures as well as after a two-step (hot + room-temperature (RT)) irradiation