High-Temperature and High-Electron Mobility Metal-Oxide-Semiconductor Field-Effect Transistors Based on N-Type Diamond.

Diamond holds the highest figure-of-merits among all the known semiconductors for next-generation electronic devices far beyond the performance of conventional semiconductor silicon. To realize diamond integrated circuits, both n- and p-channel conductivity are required for the development of diamond complementary metal-oxide-semiconductor (CMOS) devices, as those established for semiconductor silicon. However, diamond CMOS has never been achieved due to the challenge in n-type channel MOS field-effect transistors (MOSFETs). Here, electronic-grade phosphorus-doped n-type diamond epilayer with an atomically flat surface based on step-flow nucleation mode is fabricated. Consequently, n-channel diamond MOSFETs are demonstrated. The n-type diamond MOSFETs exhibit a high field-effect mobility around 150 cm2 V-1 s-1 at 573 K, which is the highest among all the n-channel MOSFETs based on wide-bandgap semiconductors. This work enables the development of energy-efficient and high-reliability CMOS integrated circuits for high-power electronics, integrated spintronics, and extreme sensors under harsh environments.

Stress effect on the resonance properties of single-crystal diamond cantilever resonators for microscopy applications.

Micro-cantilever beams have been widely used for surface sensing applications as well as atomic force microscope. However, surface stress appears in cantilever beams due to a variety of factors such as the absorption of molecules, temperature variations, materials imperfectness, and the fabrication process. Single-crystal diamond (SCD) has been regarded as an ideal material for cantilever sensors through the surface effect due to the outstanding mechanical rigidity and chemical inertness. In this paper, the authors report on the SCD cantilever beams fabricated by a smart-cut method with high quality factors up to 14 000 and stress characterization by surface geometry curvature observation and Raman microscopy. Although both surface geometry profile and Raman shift show the existence of surface stress in the SCD cantilever beams, the resonance properties are little influenced and maintain excellent rigidity and high quality. Therefore, the SCD-on-SCD resonator provides a promising platform for high-reliability microscopy applications.

Effect of Deep-Defects Excitation on Mechanical Energy Dissipation of Single-Crystal Diamond.

The ultrawide band gap of diamond distinguishes it from other semiconductors, in that all known defects have deep energy levels that are less active at room temperature. Here, we present the effect of deep defects on the mechanical energy dissipation of single-crystal diamond experimentally and theoretically up to 973 K. Energy dissipation is found to increase with temperature and exhibits local maxima due to the interaction between phonons and deep defects activated at specific temperatures. A two-level model with deep energies is proposed to explain well the energy dissipation at elevated temperatures. It is evident that the removal of boron impurities can substantially increase the quality factor of room-temperature diamond mechanical resonators. The deep energy nature of the defects bestows single-crystal diamond with outstanding low intrinsic energy dissipation in mechanical resonators at room temperature or above.

Strain-enhanced high Q-factor GaN micro-electromechanical resonator.

We report on a highly sensitive gallium nitride (GaN) micro-electromechanical (MEMS) resonator with a record quality factor (Q) exceeding 105 at the high resonant frequency (f) of 911 kHz by the strain engineering for the GaN-on-Si structure. The f of the double-clamped GaN beam bridge is increased from 139 to 911 kHz when the tensile stress is increased to 640 MPa. Although it is usually regarded that the energy dissipation increases with increasing resonant frequency, an ultra-high Q-factor which is more than two orders of magnitude higher than those of the other reported GaN-based MEMS is obtained. The high Q-factor results from the large tensile stress which can be intentionally introduced and engineered in the GaN epitaxial layer by utilizing the lattice mismatch between GaN and Si, leading to the stored elastic energy and drastically decreasing the energy dissipation. The developed GaN MEMS is further demonstrated as a highly sensitive mass sensor with a resolution of 10-12 g/s through detecting the microdroplet evaporation process. This work provides an avenue to improve the f × Q product of the MEMS through an internally strained structure.

Rebuilding of destroyed spin squeezing in noisy environments.

We investigate the process of spin squeezing in a ferromagnetic dipolar spin-1 Bose-Einstein condensate under the driven one-axis twisting scheme, with emphasis on the detrimental effect of noisy environments (stray magnetic fields) which completely destroy the spin squeezing. By applying concatenated dynamical decoupling pulse sequences with a moderate bias magnetic field to suppress the effect of the noisy environments, we faithfully reconstruct the spin squeezing process under realistic experimental conditions. Our noise-resistant method is ready to be employed to generate the spin squeezed state in a dipolar spin-1 Bose-Einstein condensate and paves a feasible way to the Heisenberg-limit quantum metrology.

[Expression and clinical significance of calcium-binding protein S100A9 in breast cancer].

AIM: To investigate the expression and clinical significance of calcium-binding protein S100A9 in the patients of breast cancer. METHODS: The serum S100A9 level from 39 cases of preoperative breast cancer, 15 postoperative patients, and 10 healthy women was detected by ELISA. Immunohistochemistry was used to detect the S100A9 expression in 12 specimens of breast cancer tissues. RESULTS: The serum S100A9 level was significantly higher in the preoperative breast cancer patients than that in the healthy women (P<0.01) and the postoperative breast cancer patients(P<0.01). The serum S100A9 level of the breast cancer patients with lymph node metastasis was significantly higher than those without lymph node metastasis (P<0.01). S100A9 level in the serum was related to patient age, tumour size, histological grade, and pathological type (P<0.01). The expression of S100A9 protein in breast cancer tissues was significantly higher than that in paracancerous benign breast tissues. CONCLUSION: The expression of S100A9 significantly increases in the serum and tissues of patients with breast cancer, which indicates that S100A9 may function as a marker of diagnosis and treatment effect in breast cancer.

[Serological antibodies comparison of a hepatitis E outbreak].

OBJECTIVE: To compare the serological characters of an outbreak of hepatitis E and evaluate sensitivity and specificity of anti-HEV E2-IgM. METHODS: The sera collected from the employees of an outbreak unit were detected for anti-HEV E2-IgM and IgG, and the serum samples from a neighboring department were used as control. The results detected with anti-HEV E2-IgM, IgG and Genelab anti-HEV IgM, IgG in some samples were compared. RESULTS: The positive rate of anti-HEV E2-IgM in the control group was 0.11%. The results between the positive and the negative samples can be distinguished easily. The specificity of anti-HEV E2-IgM is about 99.89%. The positive rate of anti-HEV E2-IgM in outbreak stricken population was 8.66%, significantly higher than that in the control group (P < 0.001). The results from HEV patients' serial samples in the outbreak unit showed that the anti-HEV E2-IgM titer was high 30-60 days after the infected and then declined clearly. The positivity seemed unrelated to neither sex nor age. Among the 115 positive to anti-HEV E2-IgM, 27 were negative to Genelab anti-HEV IgG, the fact indicated a rather high risk of misdiagnosis of about 23.48%. In the 179 randomized samples of the control group, the positive rate of Genelabs anti-HEV IgG was about 11.17%. In 110 samples for the positive anti-HEV E2-IgM, the positive ratio of Genelabs anti-HEV IgG was about 76.36%, and that of Genelabs anti-HEV IgM only 69.09%. There were 16 samples negative for both Genelabs anti-HEV IgG and IgM. The ratio of the difference between the Genelabs anti-HEV IgG and IgM was about 25.45%. CONCLUSION: The specificity of anti-HEV E2-IgM was about 99%, and false positive rate was low. The sensitivity of anti-HEV E2-IgM in acute hepatitis E infection was 25%-30% higher than that of Genelabs anti-HEV IgM,IgG. The infected persons in the outbreak unit can be preferably distinguished from the non-infected persons by anti-HEV E2-IgM. Anti-HEV E2-IgM can image the characters of the outbreak of HEV and played a great role in the control of outbreak and in the early diagnosis for hepatitis E.

[Serological characteristics of a hepatitis E outbreak].

OBJECTIVE: To look into the serological characteristics of a hepatitis E outbreak. METHODS: Sera from the first five patients with acute icteric hepatitis who developed the disease successively within ten days and the 1,675 employees routinely having their lunch in a dining hall of a department (outbreak population) were examined for anti.HEV IgM and IgG at 26th days after the outbreak, and the 883 employees of a neighboring department not having their lunch in the hall were selected as control (control population). RESULTS: The five patients were all positive for anti-HEV IgM and IgG. The positive rates of anti-HEV IgM and IgG in outbreak population were 8.7% and 38.4% respectively, both significantly higher than those in control population which were only 0.1% and 28.6%. The numbers with abnormal ALT in the 145 individuals with anti-HEV IgM(+) of outbreak population were significantly higher than those in the IgM(-) individuals of the same group as well as in control, while the abnormal ALT ratio in the IgM(-) individuals of the outbreak was not higher than that in control. The results from the four patients' serial sera showed that the anti-HEV IgM titers declined gradually and were undetectable at about 4th month after infection, and the IgG titers increased to peak in about 2-3 months after infection, then declined very slowly. The mean IgG titer of the anti-HEV IgM(+) individuals was significantly higher than that of the IgM(-) but IgG(+) individuals in outbreak population, and the latter was significantly higher than the IgG(+) individuals in control, which suggested that the post-infection individuals' immunities to HEV were boosted during the outbreak. There was no difference between sex or age groups for the anti-HEV IgM(+) ratio, but the abnormal ALT was much more frequent in the anti-HEV IgM(+) male than in the female, and no difference was observed between age groups. CONCLUSION: The pathogen of the outbreak of acute icteric hepatitis was hepatitis E virus and associated with food intake. Anti-HEV IgM and IgG were used not only for diagnosis of hepatitis E but also for surveilance in mass population. The attack risk was not associated with age or sex, but the abnormal ALT was much more frequent fresh infectors in male.