Hai-Dang Trinh

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.

High quality Ge thin film grown by ultrahigh vacuum chemical vapor deposition on GaAs substrate

High-quality epitaxial Ge films were grown on GaAs substrates by ultrahigh vacuum chemical vapor deposition. High crystallinity and smooth surface were observed for these films by x-ray diffraction, transmission electron microscopy, and atomic force microscopy. Direct band gap emission (1550 nm) from this structure was detected by photoluminescence. Valence band offset of 0.16 eV at the Ge/GaAs interface was measured by x-ray photoelectron spectroscopy. N-type arsenic self-doping of 1018/cm−3 in the grown Ge layers was determined using electrochemical capacitance voltage measurement. This structure can be used to fabricate p-channel metal-oxide-semiconductor field-effect transistor for the integration of Ge p-channel device with GaAs n-channel electronic device.

Effects of Wet Chemical and Trimethyl Aluminum Treatments on the Interface Properties in Atomic Layer Deposition of Al2O3 on InAs

The reduction of native oxides on an InAs surface using various wet and dry chemical treatments, including hydrochloric acid (HCl) treatment, sulfide treatment, and in situ trimethyl aluminum (TMA) treatment before the atomic layer deposition (ALD) of Al2O3 on InAs is studied. X-ray photoelectron spectrum (XPS) results show that the effect of surface cleaning by TMA was apparent almost after the first pulse but that TMA cleaning is not as effective as wet chemical surface cleaning. The combination of wet chemical treatment and TMA pretreatment is the most effective method for InAs surface cleaning, as indicated by the XPS analysis. Capacitance–voltage (C–V) and current density–voltage (J–V) characteristics on metal–oxide–semiconductor capacitance (MOSCAP) structures were also investigated to evaluate the Al2O3/n-InAs interface quality after different surface treatments, and the results are consistent with the XPS analysis.

Effect of Postdeposition Annealing Temperatures on Electrical Characteristics of Molecular-Beam-Deposited HfO2 on n-InAs/InGaAs Metal-Oxide-Semiconductor Capacitors

The electrical characteristics of molecular-beam-deposited HfO2/n-InAs/InGaAs metal–oxide–semiconductor capacitors with different postdeposition annealing (PDA) temperatures (400–550 °C) are investigated. Results show that the sample with the PDA temperature of 500 °C exhibits the best capacitance–voltage (C–V) behavior with small frequency dispersion and small hysteresis. The X-ray photoelectron spectroscopy (XPS) spectra show the reduction of the amount of As-related oxides to below the XPS detection level when the PDA temperature is up to 500 °C. As the PDA temperature was increased to above 500 °C, As and In atoms seem to diffuse significantly into HfO2, resulting in the degradation of C–V behavior.

Growth of High-Quality In0:4Ga0:6N Film on Si Substrate by Metal Organic Chemical Vapor Deposition

High-quality In0.4Ga0.6N film grown on GaN/AlN/Si(111) templates was obtained by metal organic chemical vapor deposition (MOCVD) with negligible phase separation. A template of high-quality GaN grown on a Si(111) substrate using AlN buffer layers was used for subsequent In0.4Ga0.6N growth. The GaN layer was 0.6 µm thick with rocking-curve full width at half maximum (FWHM) for a GaN(002) peak better than 430 arcsec. The In0.4Ga0.6N film grown was 0.3 µm thick with a dislocation density of 6×107 cm-2 and X-ray (ω–2θ) FWHM better than 130 arcsec.

Effect of annealing processes on the electrical properties of the atomic layer deposition Al2O3/In0.53Ga0.47As metal oxide semiconductor capacitors

The influence of different annealing processes including post deposition annealing (PDA) and post metallization annealing (PMA) with various temperatures (250–400 °C) and ambient [N2 and forming gas (FG)] on the electrical characteristics of Pt/Al2O3/In0.53Ga0.47As MOSCAPs are systemically studied. Comparing to samples underwent high PDA temperature, the higher leakage current has been observed for all of samples underwent high PMA temperature. This has resulted in the degradation of capacitance–voltage (C–V) behaviors. In conjunction with the current–voltage (J–V) measurement, depth profiling Auger electron spectroscopy (AES) and high-resolution transmission electron microscopy (HRTEM) analyses evidence that the out-diffusion of metal into oxide layer is the main source of leakage current. The noticeable passivation effect on the Al2O3/InGaAs interface has also been confirmed by the samples that underwent PDA process.

Investigation of Characteristics of Al2O3/n-In x Ga1−x As (x = 0.53, 0.7, and 1) Metal–Oxide–Semiconductor Structures

The electrical properties of Al2O3/n-InGaAs metal–oxide–semiconductor capacitors (MOSCAPs) with In content of 0.53, 0.7, and 1 (InAs) have been investigated. Results show small capacitance–voltage (C–V) frequency dispersion in accumulation (1.70% to 1.85% per decade) for these MOSCAPs, mostly being assigned to border traps in Al2O3. With higher In content, shorter minority-carrier response time and smaller C–V hysteresis are observed. The reduction of C–V hysteresis might be related to the reduction of Ga-bearing oxides in Al2O3/InGaAs interfaces as indicated by x-ray photoelectron spectroscopy.

Demonstrating 1 nm-oxide-equivalent-thickness HfO2/InSb structure with unpinning Fermi level and low gate leakage current density

In this work, the band alignment, interface, and electrical characteristics of HfO2/InSb metal-oxide-semiconductor structure have been investigated. By using x-ray photoelectron spectroscopy analysis, the conduction band offset of 1.78 ± 0.1 eV and valence band offset of 3.35 ± 0.1 eV have been extracted. The transmission electron microscopy analysis has shown that HfO2 layer would be a good diffusion barrier for InSb. As a result, 1 nm equivalent-oxide-thickness in the 4 nm HfO2/InSb structure has been demonstrated with unpinning Fermi level and low leakage current of 10−4 A/cm−2. The Dit value of smaller than 1012 eV−1cm−2 has been obtained using conduction method.

In x Ga 1−x As materials for post CMOS application: Materials and device aspects

High mobility In_xGa_1-xAs material is one of the most promising candidates as channel material for post CMOS device applications. In this presentation, In_xGa_1-xAs material based MOS capacitors will be studied for possible applications for future III-V MOSFET, TFET and FINFET devices. To improve the gate leakage of the In_xGa_1-xAs MOSCAP, the combination of wet chemical treatment and in-situ trimethyl aluminum (TMA) pretreatment was found to be the most effective method for In_xGa_1-xAs surface cleaning to achieve a fully inverted In_xGa_1-xAs MOSCAP for post CMOS digital applications. In addition, a high-k composite oxide composed of La₂O₃ and HfO₂ is investigated for In_xGa_1-xAs metal-oxide-semiconductor (MOS) capacitor application. The composite oxide was formed by depositing five layers of La₂O₃(0.8 nm)/ HfO₂(0.8 nm) on In_xGa_1-xAs with post deposition annealing at 500 °C. The MOS capacitors fabricated show good inversion behavior, high capacitance, low leakage current, with excellent interface trap density (D_it) of 7.0 × 10¹¹ cm^-2eV^-1, small hysteresis of 200 mV and low capacitance equivalent thickness of 2.2 nm at 1 kHz were also achieved.

Ge epitaxial films on GaAs (100), (110), and (111) substrates for applications of CMOS heterostructural integrations

Epitaxial Ge films were grown on GaAs (100), (110), and (111) substrates by using ultra-high vacuum chemical vapor deposition and studied with various methods. The incubation times and growth rates were quite different for these three GaAs substrates because the surface arsenic coverage on GaAs and hydrogen desorption energy on Ge are different for each orientation. High-resolution x-ray diffraction measurements, direct band-gap emission of photoluminescence measurements, and cross-sectional transmission electron microscopy showed that the Ge films had high crystal quality, low defect density, and sharp Ge/GaAs interfaces. In this study, atomic force microscopy analysis found that the Ge films grow on GaAs (100) and (111) via the Frank van der Merwe mode, while the Ge film grows on GaAs (110) via the Volmer-Weber mode at the initial growth stage, which can be explained by the thermodynamic theory of capillarity. Interestingly, when the thickness of the Ge film on the GaAs (110) substrate increases to ∼220...