Y. C. Lin

The influences of surface treatment and gas annealing conditions on the inversion behaviors of the atomic-layer-deposition Al2O3/n-In0.53Ga0.47As metal-oxide-semiconductor capacitor

The inversion behaviors of atomic-layer-deposition Al2O3/n-In0.53Ga0.47As metal-oxide-semiconductor capacitors are studied by various surface treatments and postdeposition annealing using different gases. By using the combination of wet sulfide and dry trimethyl aluminum surface treatment along with pure hydrogen annealing, a strong inversion capacitance-voltage (C-V) response is observed, indicating a remarkable reduction in interface trap state density (Dit) at lower half-part of In0.53Ga0.47As band gap. This low Dit was confirmed by the temperature independent C-V stretch-out and horizontal C-V curves. The x-ray photoelectron spectroscopy spectra further confirm the effectiveness of hydrogen annealing on the reduction of native oxides.

Electrical Characterization of

Ex situ sulfide and HCl wet chemical treatments in conjunction with in situ trimethyl aluminum (TMA) pretreatment were performed before the deposition of Al2O3 on n-InAs surfaces. X-ray photoelectron spectroscopy analyses show a significant reduction of InAs native oxides after different treatments. The capacitance-voltage C- V characterization of Al2O3/n-InAs structures shows that the frequency dispersion in the accumulation regime is small (<; 0.75%/dec) and does not seem to be significantly affected by the different surface treatments, whereas the latter improves depletion and inversion behaviors of the n-channel metal-oxide-semiconductor capacitors. The interface trap density profiles extracted from the simulation mainly show donorlike interface states inside the InAs band gap and in the lower part of the conduction band. The donorlike traps inside the InAs band gap and in the lower part of the conduction band were significantly reduced by using wet-chemical-plus-TMA treatments, in agreement with C-V characteristics.

\hbox{Al}_{2} \hbox{O}_{3}

This study explores the effects of both Oxygen and temperature on the carrier dynamics of isoelectronic ZnSe1−xOx (x=0.027 and 0.053) semiconductors using photoluminescence (PL) and time-resolved PL spectroscopy. We find that the Kohlrausch law is highly consistent with the complex decay traces induced by isoelectronic O traps, and the mechanism of carrier recombination undergoes a complicated change from trapped to free excitons with the increase in temperature. Complex recombination processes are clarified using the relaxation model based on various decay channels. These findings are consistent with the initial fall in the stretching exponent β followed by its monotonic increase with increasing temperature.

/n-InAs Metal–Oxide–Semiconductor Capacitors With Various Surface Treatments

The growth of the AlGaSb∕InAs high-electron-mobility transistor (HEMT) epitaxial structure on the Si substrate is investigated. Buffer layers consisted of UHV/chemical vapor deposited grown Ge∕GeSi and molecular beam epitaxy-grown AlGaSb∕AlSb∕GaAs were used to accommodate the strain induced by the large lattice mismatch between the AlGaSb∕InAs HEMT structure and the Si substrate. The crystalline quality of the structure grown was examined by x-ray diffraction, transmission electron microscopy, and atomic force microscopy. Finally, very high room-temperature electron mobility of 27300cm2∕Vs was achieved. It is demonstrated that a very-high-mobility AlGaSb∕InAs HEMT structure on the Si substrate can be achieved with the properly designed buffer layers.

Carrier dynamics in isoelectronic ZnSe1−xOx semiconductors

Kohlrausch’s stretched exponential law correlates well with the photoluminescence (PL) decay profiles of ZnSe1−xTex. As the Te concentration increases, the stretching exponent β initially declines and then monotonically increases. This result can be understood using the hopping-transport and energy transfer model. The increase in the number of isoelectronic Te localized traps can reduce the PL decay rate and increase the linewidth, whereas the hybridization of the Te localized states with the valence-band edge states causes a reduction in both the lifetime and linewidth.

Growth of very-high-mobility AlGaSb∕InAs high-electron-mobility transistor structure on si substrate for high speed electronic applications

This study investigates the dependence of Forster resonance energy transfer (FRET) on donor-acceptor (D/A) concentration ratios in mixed-size CdTe quantum dots (QDs) films by using photoluminescence (PL) and time-resolved PL spectroscopy. Experimental results indicate that an increasing donor concentration significantly quenches the emission intensity and lifetime in donor QDs and enhances that in acceptor QDs, providing clear evidence of increased FRET efficiency. When D/A ratio exceeds 6, however, the emission intensity and the lifetime of acceptors start to decline, reflecting a decreasing FRET efficiency because of a markedly declining availability of acceptor QDs.

Time-resolved photoluminescence of isoelectronic traps in ZnSe1−xTex semiconductor alloys

Antireflective gate structures of polycrystalline silicon (poly-Si) and silicon dioxide films enable postimplantation green continuous-wave laser annealing of all Si regions of green laser-crystallized panel Si transistors. About 40% of the incident laser-energy penetrates to the channels, owing to antireflective gate structures with the absorptive gate poly-Si, while 65% of the incident laser-energy enters the source/drain regions because of Fresnel reflections at the air/source (drain) interfaces. Such inverted laser-energy profiles and ascendant defect distributions along the channels/junctions/contact regions, yielded continuous, improved epilike Si microstructures over the entire active layer. The electron mobility of the transistors, 620cm2∕Vs, approaches that of integrated-circuits transistors.

Effect of donor-acceptor concentration ratios on nonradiative energy transfer in closely packed CdTe quantum dots

This investigation characterizes electrical characteristics of continuous-wave green laser-annealed single-grainlike silicon thin-film transistors in relation to trap-state densities. As laser power increases, highly crystalline channels form, reducing tail-state densities to as low as 3×1019eV−1cm−3. This occurrence is responsible for high field-effect electron mobility of 284cm2∕Vs. In contrast, increasing laser power initially reduces the deep-state density and then increases it to 3×1016eV−1cm−3. This reversal in deep-state density and thus in the subthreshold slope as well as a saturating reduction in threshold voltage are associated with the formation of extra interface defects caused by laser-crystallization-enhanced surface roughness.

Enhanced green laser activation by antireflective gate structures in panel transistors

The uniformly doped and the /spl delta/-doped In/sub 0.52/Al/sub 0.48/As/In/sub 0.6/Ga/sub 0.4/As metamorphic high-electron mobility transistors (MHEMTs) were fabricated, and the dc characteristics and the third-order intercept point (IP3) of these devices were measured and compared. Due to more uniform electron distribution in the quantum-well region, the uniformly doped MHEMT exhibits a flatter transconductance (G/sub m/) versus drain-to-source current (I/sub DS/) curve and much better linearity with higher IP3 and higher IP3-to-P/sub dc/ ratio as compared to the /spl delta/-doped MHEMT, even though the /spl delta/-doped device exhibits higher peak transconductance. As a result, the uniformly doped MHEMT is more suitable for communication systems that require high linearity operation.

Trap-state density in continuous-wave laser-crystallized single-grainlike silicon transistors

Type-II diluted magnetic semiconductor ZnMnTe quantum dots (QDs) in ZnSe matrix grown by molecular beam epitaxy were investigated by conventional and magnetophotoluminescence (PL) spectroscopy. The QD emission exhibits a type-II characteristic in excitation power dependence of PL peak energy. A nonzero circular polarization of PL at the absence of magnetic field was observed. This phenomenon is attributed to the accumulation of interface charges confined in adjacent layers. The magneto-optical measurement demonstrates a magnetic-induced degree of circular polarization in the PL spectra, indicating the Mn incorporation into the QD system.