Showing papers by "Shuit-Tong Lee published in 1993"
TL;DR: Experimental phonon features of H-free and partially H-terminated diamond surfaces agree well with scaled phonon frequencies of theoretically predicted modes for similarly reconstructed silicon surfaces, and several modes not detected on silicon surfaces are observed on diamond surfaces, in agreement with scaled theoretical calculations.
Abstract: The surface phonons and CH vibrational structure of diamond (100) and (111) surfaces have been examined using high-resolution electron-energy-loss spectroscopy. Experimental phonon features of (2\ifmmode\times\else\texttimes\fi{}1)-reconstructed diamond surfaces [H-free (100) and partially H-terminated (111)] agree well with scaled phonon frequencies of theoretically predicted modes for similarly reconstructed silicon surfaces. Several modes not detected on silicon surfaces are observed on diamond surfaces, in agreement with scaled theoretical calculations. Vibrational spectra from hydrogen-terminated diamond (1\ifmmode\times\else\texttimes\fi{}1) surfaces reveal several types of ${\mathrm{CH}}_{\mathit{x}}$ species, including ${\mathit{sp}}^{3}$ hybridized methyl and methylene groups, and olefinic (${\mathit{sp}}^{2}$ hybridized) methylene groups. On heating to \ensuremath{\sim}1473 K, hydrogen desorbs readily from the (100) surface. Complete removal of hydrogen from the (111) surface by repeated annealing to \ensuremath{\sim}1473 K was impossible, although (2\ifmmode\times\else\texttimes\fi{}1) reconstruction had already occurred.
124 citations
TL;DR: In this paper, a carbon doped Al0.4Ga0.6As/GaAs superlattices (SL) were annealed under different ambient As4 pressure conditions in the temperature range of 825 °C-960 C. The SL were doped with carbon to an initial acceptor concentration of ∼2.9×1019 cm−3.
Abstract: Al–Ga interdiffusion, carbon acceptor diffusion, and hole reduction were studied in carbon doped Al0.4Ga0.6As/GaAs superlattices (SL) annealed under different ambient As4 pressure conditions in the temperature range of 825 °C–960 °C. The SL were doped with carbon to an initial acceptor concentration of ∼2.9×1019 cm−3. Al–Ga interdiffusion was found to be most prominent under Ga‐rich annealing ambient conditions, with interdiffusivity values, DAl–Ga, turned out to be about two orders of magnitude smaller than those predicted by the Fermi‐level effect model. Under As‐rich ambient conditions, the DAl–Ga values are in approximate agreement with those predicted by the Fermi‐level effect model. The hole concentrations in the SL decreased significantly after annealing under As‐rich and As‐poor ambient conditions, while those after annealing in the Ga‐rich ambient were almost totally intact. By analyzing the measured hole concentration profiles, it has been found that both carbon acceptor diffusion and reduction ...
27 citations
Patent•
08 Oct 1993TL;DR: A semiconductor device having in a body of a group III-V semiconductor material at least one isolation region which is stable at temperatures up to about 900° C is defined in this paper.
Abstract: A semiconductor device having in a body of a group III-V semiconductor material at least one isolation region which is stable at temperatures up to about 900° C. The isolation region is formed of ions of a group III or V element which are implanted into the body and then thermally annealed at a temperature of between 650° C. and 900° C. This provides the regions with voids which remove free carriers and makes the region highly resistive.
8 citations
TL;DR: Boron depth distributions are reported for MeV implants into silicon through a variety of masking materials as mentioned in this paper, which indicate that TRIM overestimates the energy loss of MeV boron ions as they pass through photoresist and/or silicon dioxide.
Abstract: Boron depth distributions are reported for MeV implants into silicon through a variety of masking materials. Silicon is implanted with boron through a 0.1-μm-thick layer of thermally grown silicon dioxide. Secondary ion mass spectrometry (SIMS) shows the projected ranges agree within 10% with data reported in the literature and with results from the computer program TRIM. Silicon dioxide, photoresist, and metal layers are used to mask the high-energy boron implants. The SIMS results indicate that TRIM overestimates the energy loss of MeV boron ions as they pass through photoresist and/or silicon dioxide.
TL;DR: In this article, the authors studied carbon-doped Al0.4Ga0.6As/GaAs superlattices (SL) and found that carbon acceptor diffusion and reduction have occurred during annealing, with both depending on As4 pressure values to the one quarter power.
Abstract: Al-Ga interdiffusion, carbon acceptor diffusion, and hole reduction were studied in carbon-doped Al0.4Ga0.6As/GaAs superlattices (SL). Al-Ga interdiffusion was found to be most prominent for Ga-rich annealing, with the hole concentrations in the SL almost intact during annealing. For As-rich annealing, the interdiffusivity values, DAl-Ga, are in approximate agreement with those predicted by the Fermi-level effect model, and the hole concentrations in the SL decreased dramatically after annealing. By analyzing the measured hole concentration profiles, it was found that both carbon acceptor diffusion and reduction have occurred during annealing, with both depending on As4 pressure values to the one quarter power. These As4pressure dependencies indicate that carbon diffuses via the interstitial-substitutional mechanism while hole reduction is governed by a precipitation mechanism.