Proton Irradiation Effects on Strained Sil . xGex / Si Heferostructures
نویسندگان
چکیده
Proton irradiation effects on strained Si 1.XGeX/Si heterostructures have been studied. For the experiment, p+-Sil -xGex/p--Si heterojunction diodes were fabricated by molecular beam epitax y (MBE) growth of strained p+boron doped SiGe layers on p -Si(100) substrates. Due to the valence band discontinuity between SiGe and Si layers, and degenerate doping in the SiGe layer, the characteristics of these heterojunction diodes are similar to those of metal-semiconductor Schottky barrier diodes. The SiGe/Si heterojunction diodes are irradiated by 1 Mrad of protons at 1 and 8.5 MeV energies. The current-voltage (I-V) characteristics are measured as a function of temperature before and after irradiation. I-V characteristics show a decrease of the reverse bias leakage current after irradiation. The effective heterojunction barrier heights (@b) and Richardson constants (A**) are measured before and after irradiation using activation energy measurements. The measurements show an increase of @b and A** after irradiation. The “increase of the effective barrier height is attributed to reduction of free holes in the SiGe layers due to proton induced displacement defects. The increase of effective barrier height suggests that the strain in the SiGe layers is conserved after 1 Mrad of proton irradiation.
منابع مشابه
Ballistic-electron-emission microscopy of strain nonuniformities in Si1-xGex/Si structures.
Ballistic-electron-emission microscopy (BEEM) is used to probe local conduction-band structure in strained Sil .xGq layers of pseudomorphic Sil-xGe#Si heterostmctires. The strain variation produced by a roughened Si l.xGex surface is seen as a variation of splitting between thresholds in BEEM spectroscopy. This splitting is directly related to the strain-induced conduction-band splitting in the...
متن کاملDopant diffusion in Si and SiGe
Dopant diffusion in semiconductors is an interesting phenomenon from both technological and scientific points of view. Firstly, dopant diffusion is taking place during most of the steps in electronic device fabrication and, secondly, diffusion is related to fundamental properties of the semiconductor, often controlled by intrinsic point defects: self-interstitials and vacancies. This thesis inv...
متن کاملextraction of Band Offsets in Strained Si/Strained Si1-YGey on Relaxed Si1-XGex Dual-Channel enhanced Mobility Structures
In this work, for the first time, the valence band offset, ∆EV, between strained Si and strained Si1-yGey on relaxed Si1-xGex, has been measured using a combination of experimentation and modeling. Such structures have been shown to offer large mobility enhancements for both electrons and holes, and knowledge of the band parameters is critical in order to optimize and predict device behavior [1...
متن کاملVacancy-impurity pairs in relaxed Si1−xGex layers studied by positron annihilation spectroscopy
Positron annihilation spectroscopy was applied to study relaxed P-doped n-type and undoped Si1−xGex layers with x up to 0.30. The as-grown SiGe layers were found to be defect free and annihilation parameters in a random SiGe alloy could be represented as superpositions of annihilations in bulk Si and Ge. A 2 MeV proton irradiation with a 1.6 1015 cm−2 fluence was used to produce saturated posit...
متن کاملVALENCE BAND STRUCTURE OF STRAINED-LAYER Si-Si0.5Ge0.5 SUPERLATTICES
We calculate the valence subband dispersion of Sio,5Ge,,5 Si strained layer structures grown on a Si (001) substrate and on a Si0,,5Ge0,25 buffer. We use the 6x6 Luttinger-Kohn Hamiltonian, including the effects both of strain and of the split-off band. The heavy-hole zone centre states are separated by over 60meV from the light-hole states and the highest valence subband has a low zone-centre ...
متن کامل