InGaAs buried channel metal-oxide-semiconductor field-effect transistors for low-power logic applications

As Silicon complementary-oxide-semiconductor (CMOS) devices scale into the sub-22nm regime, severe short channel effects and power-dissipation constraints lead to huge challenges. To maintain high switching speed and lower power consumption, III-V high mobility channel materials are currently under intensive investigation due to the high electron injection velocity. Although tremendous advances are being made, the grand challenges, such as the lack of a reliable metal/high-k gate stack, large device footprint, parasitic resistance and capacitance, still hinder a viable III-V technology for logic applications. The major objective of this dissertation is to experimentally explore deeply scaled high performance InGaAs buried channel MOSFETs on Silicon substrates. Firstly, oxide/InAlAs interface quality was optimized by surface pretreatment and passivation. InGaAs surface channel and recessed-gate buried channel MOSFETs were fabricated. Improved device performance was achieved with the buried channel architecture. However, it was still limited by the large parasitic resistance, gate-recess etching process and long channel length. Source/drain (S/D) selective regrowth is a promising technique to solve these problems. The second part of this dissertation focuses on the development of a gate-last process incorporating selective S/D regrowth. Sub-micron channel-length devices were achieved with this process by optimizing the optical lithography and lateral over-etching. The impact of vertical scaling of gate dielectric and device active layers was investigated. A low-temperature post metallization annealing process was developed to achieve enhancement-mode (E-mode) operation. The optimized device fabrication process resulted in high-performance 120nm E-mode InGaAs MOSFET on GaAs substrate with a record-high transconductance of 1881 mS/mm at Vds=0.5V. By further optimizing the fabrication process, 30nm E-mode InGaAs MOSFET on Silicon substrates was successfully demonstrated with a high transconductance of 1697 mS/mm at Vds=0.5V and a record-low on-resistance of 157 Ω·μm. To the best of our knowledge, this is the first high-performance III-V MOSFET with channel length down to sub-50nm. Benchmarking of logic figures of merit with state-of-the-art InGaAs MOSFETs in literature was then presented. Our devices exhibited highly competitive performance, indicating that combining buried InAlAs/InGaAs quantum-well channel with S/D regrowth is promising for future low-power logic applications

Inverted-Type InGaAs Metal-Oxide-Semiconductor High-Electron-Mobility Transistor on Si Substrate with Maximum Drain Current Exceeding 2 A/mm

Inverted-type In0.51Al0.49As/In0.53Ga0.47As metal-oxide-semiconductor high-electron-mobility transistor grown by metal organic chemical vapor deposition on a Si substrate was demonstrated. 8 nm atomic-layer-deposited Al2O3 was used as gate dielectric. N++ InGaAs with an electron density of 4.5 x 10(19) cm(-3) was selectively regrown in the source/drain regions to reduce parasitic resistance while eliminating the conventional gate recess etching. 130-nm channel-length devices have exhibited a drain current up to 2.03 A/mm at V-ds = 0.6 V and an ultralow on-resistance of 163 Omega mu m. An effective mobility of 2975 cm(2) V-1 s(-1) was also extracted, indicating the high-quality epitaxial growth by metal organic chemical vapor deposition. (C) 2012 The Japan Society of Applied Physic

InGaAs MOS-HEMTs on Si substrates grown by MOCVD

We present In0.53Ga0.47As-channel metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs) on Si substrates grown by metalorganic chemical vapor deposition (MOCVD) for the first time. Atomic-layer-deposited (ALD) Al2O3 was used as gate dielectric. A low-temperature process was developed to achieve good ohmic contact and maintain material integrity. A 1-μm gate-length device shows a maximum drain current of 415 mA/mm and extrinsic transconductance of 329 mS/mm. The gate leakage current is 7.3 nA/mm at gate bias of -3V, which is six orders of magnitude lower than that of the conventional HEMT using the same heterostructure. © VDE VERLAG GMBH

High-Performance Inverted In0.53Ga0.47As MOSHEMTs on a GaAs Substrate With Regrown Source/Drain by MOCVD

We report inverted-type In0.51Al0.49As/In0.53Ga0.47As MOSHEMTs heteroepitaxially grown on GaAs substrates by metal-organic chemical vapor deposition. High 2-D electron gas Hall mobility values of 8200 cm(2)/V . s at 300 K and 33 900 cm(2)/V . s at 77 K have been achieved. The buried quantum-well channel design is combined with selectively regrown source/drain (S/D) using a gate-last process. A 120-nm-channel-length MOSHEMT exhibited a maximum drain current of 1884 mA/mm, peak transconductance of 1126 mS/mm at V-ds = 0.5 V, and a subthreshold slope of 135 mV/dec at V-ds = 0.05 V. With the regrown S/D, an ultralow ON-state resistance of 156 Omega . mu m was obtained

30-nm Inverted In0.53Ga0.47As MOSHEMTs on Si Substrate Grown by MOCVD With Regrown Source/Drain

We report inverted-type In0.51Al0.49As/In0.53Ga0.47As MOSHEMTs grown by MOCVD on a Si substrate. n(++) InGaAs with an electron density of 4.5 x 10(19) cm(-3) was selectively regrown in the source/drain regions to reduce parasitic resistance while eliminating the conventional gate recess etching. A 30-nm-channel-length device was successfully demonstrated with a maximum drain current of 1698 mA/mm, a peak transconductance of 1074 mS/mm at V-ds = 0.5 V, a subthreshold slope of 172 mV/dec at V-ds = 0.05 V, and a record-low on-resistance of 133 Omega . mu m. An effective mobility of 4805 cm(2)/V . s was also extracted, indicating the high-quality metamorphic growth by MOCVD. In addition, the scalability of the inverted MOSHEMT on a Si substrate from 1 mu m down to 30 nm was investigated

30nm Enhancement-mode In0.53Ga0.47As MOSFETs on Si Substrates Grown by MOCVD Exhibiting High Transconductance and Low On-resistance

This paper describes the development of 30nm enhancement-mode In0.53Ga0.47As MOSFETs grown on Si substrates featuring Al2O3/InAlAs composite gate stack with extrinsic transconductance of 1700mS/mm at V-ds=0.5V and on-resistance of 157 Omega.mu m. A low-temperature process of post metallization annealing has been developed to achieve enhancement-mode operation. Capacitance-Voltage measurements and TEM observation were carried out to investigate the mechanisms of threshold voltage shift. Furthermore, device scalability down to 30nm is reported

Material and Device Characteristics of Metamorphic In0.53Ga0.47As MOSHEMTs Grown on GaAs and Si Substrates by MOCVD

We report a comparison of material and device characteristics of metamorphic In0.53Ga0.47As channel metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs) grown on GaAs and Si substrates by metal-organic chemical vapor deposition. A gate-last process was developed to simplify the fabrication of nanoscale channel length devices. Selective source/drain regrowth was incorporated to reduce parasitic resistances. Post-metallization annealing (PMA) was utilized to mitigate the weakened gate electrostatic control in the buried channel. The effect of PMA on the Ti/Al2O3 gate-stack was investigated in detail. Record-low ON-state resistance of 132 and 129 Omega . mu m has been achieved in enhancement-mode InGaAs MOSHEMT on GaAs and on Si substrate, respectively. A 120-nm channel length device on GaAs exhibited a figure of merit Q (g(m)/SS) of 12, whereas a 60-nm channel length In0.53Ga0.47As MOSHEMT on Si demonstrated Q up to 14

Preparation and Characterization of Novel Polyvinylidene Fluoride/2-Aminobenzothiazole Modified Ultrafiltration Membrane for the Removal of Cr(VI) in Wastewater

Hexavalent chromium is one of the main heavy metal pollutants. As the environmental legislation becomes increasingly strict, seeking new technology to treat wastewater containing hexavalent chromium is becoming more and more important. In this research, a novel modified ultrafiltration membrane that could be applied to adsorb and purify water containing hexavalent chromium, was prepared by polyvinylidene fluoride (PVDF) blending with 2-aminobenzothiazole via phase inversion. The membrane performance was characterized by evaluation of the instrument of membrane performance, infrared spectroscopy (FTIR), scanning electron microscope (SEM), and water contact angle measurements. The results showed that the pure water flux of the PVDF/2-aminobenzothiazole modified ultrafiltration membrane was 231.27 L/m2·h, the contact angle was 76.1°, and the adsorption capacity of chromium ion was 157.75 µg/cm2. The PVDF/2-aminobenzothiazole modified ultrafiltration membrane presented better adsorption abilities for chromium ion than that of the traditional PVDF membrane

Two-Sex Life Table Analysis of the Predator <i>Arma chinensis</i> (Hemiptera: Pentatomidae) and the Prediction of Its Ability to Suppress Populations of <i>Scopula subpunctaria</i> (Lepidoptera: Geometridae)

Scopula subpunctaria (Herrich-Schaeffer) (Lepidoptera: Geometridae) is a leaf-eating pest in tea plantations that often causes serious economic losses. Arma chinensis (Fallou) (Hemiptera: Pentatomidae) as a polyphagous insect has become one of the main biological control agents for tea plantation pests due to its wide feeding habit, predatory ability, and adaptability. However, studies related to the predation using A. chinensis on the third instar S. subpunctaria have not been reported. In this study, we used the age-stage, two-sex life table method to analyze the developmental duration and fecundity of S. subpunctaria fed on tea, and A. chinensis fed on third instar S. subpunctaria larvae, under a 25 °C regime. The growth, development, survival, fecundity, and predation rates of the insect populations were investigated. The results showed that the predator and the prey can complete their respective life histories, but the developmental durations at each stage were different, and the developmental stages overlapped significantly. In addition, we used the computer program TIMING-MSChart to project the stage structure and the total population size of A. chinensis and S. subpunctaria. We also simulated the population changes of S. subpunctaria using an A. chinensis intervention. These results showed that S. subpunctaria can support A. chinensis to finish its life history and A. chinensis has great potential to control S. subpunctaria. This study contributes to the understanding of the biological characteristics of S. subpunctaria and provides a theoretical basis for releasing A. chinensis in the field to suppress S. subpunctaria