A NEW EPR DEFECT IN NEUTRON-IRRADIATED FZ-SILICON AND HYDROGEN PASSIVATION EFFECT

A new EPR center having C2v symmetry and S=1, labeled as Si-PK3, has been observed for the first time in neutron-irradiated FZ-silicon. The spectra start to appear after 150℃ annealing and disappear at 500℃. The principal values of tensor g and D are determined. The microscopic model is proposed to be a trivacancy chain along the 〈110〉-direction with an oxygen atom situated in the middle. The annealing temperature of si-PK3 in hydrogencontaining samples is at least by 150℃ lower than that of other samples.

Analysis of single frequency modulation for passive hydrogen maser

Based on the theory of the passive hydrogen maser, along with the technology of frequency modulation and modulation transfer spectroscopy, the theoretical expression of the single frequency modulation for the passive hydrogen maser and the function of the cavity and H line error signals separation are derived, which are basically coincident with the experiment. The absorption and dispersion spectrum curves with different resonance widths show that the cavity and hydrogen transition serve as discriminators, and the two error signals can be separated. Through the calculations of the two error signals in the passive hydrogen maser, it analyzes the traditional method of the two error signals separation, and then describes a new improved method for the passive hydrogen servo loops consisting in the use of a single modulation frequency and frequency discrimination. A null interaction of the two error signals for the new selection of the phase setting is deduced theoretically and validated by the simulation. The preliminary experimental result confirms the feasibility of this new approach, which can reduce the influence from the cavity frequency variety on the crystal oscillator and contribute significantly to the long term performance of the passive hydrogen maser.

H^+ Passivation of Poly-Si Solar CellsProcessed by Different Annealing Processes

The effects of different annealing processes on the photovoltaic (PV) properties and the spectral response as well as minority carrier lifetime in the bulk of unanalyzed PF5 ion implantation poly-Si solar cells were investigated. The different hydrogen passivation effects of defects in poly-Si induced by three heat treatment processes are reported. We used RTA-rapid thermal annealing, YAG pulse laser annealing and CTSA-classical three-step annealing for this study. The results show that cells processed by RTA (800°C, 4 sec) achieved the best PV properties and spectral response among all annealed samples. Under this precess condition, no or few defects were induced in bulk. While RTA (>-850°C for 4 sec), CTSA as well as YAG laser processes induced defects of different nature and concentration in the bulk of cells. It is further shown that hydrogen ion implantation significantly improved, the performances of poly-Si cells. It is able to efficiently remove the YAG laser induced defects in bulk. However, it cannot completely passivate the defects induced by CTSA and RTA processes.

Technology and test results of space adaptability of passive hydrogen maser

Based on the operating principle and the electric property design of the passive hydrogen maser, the technology and test results of its space adaptability are carried out under the special launch conditions and space environment. The various perturbations affecting the output frequency of such a standard used for the navigation satellite system are specified, such as magnetic field change, vibration, thermal vacuum and radiation. Through the adaptability technology in the aspects above, the security and reliability of the space passive hydrogen maser sufficiently fulfill the requirements of space operation. At present, the space passive hydrogen maser is working normally on board, indicating that the space adaptability satisfies the design requirement.

Study on hydrogen sulfide plasma passivation of 790-nm laser diode cavity surface

In order to improve the optical properties of the Ⅲ-Ⅴ laser diodes （LDs） by means of H2S plasma passivation technology, H2S plasma passivation treatment is performed on the GaAs（110） surface. The optimum passivation conditions obtained are 60-W radio frequency （RF） power and 20-min duration. So the laser cavity surfaces are treated under the optimum passivation conditions. Consequently, compared with unpassivated lasers with only AR/HR-eoatings, the catastrophic optical damage （COD） threshold value of the passivated lasers by H2S plasma treatment is increased by 33%, which is almost the same as that of （NH4）2Sx treatment. And the life-test experiment has demonstrated that this passivation method is more stable than （NH4）2Sx solution wet-passivated treatment.

Defect passivation on cast-mono crystalline screen-printed cells

Cast-mono crystalline silicon wafers contain crystallographic defects, which can severely impact the electrical performance of solar cells. This paper demon- strates that applying hydrogenation processes at moderate temperatures to finished screen print cells can passivate dislocation clusters within the cast-mono crystalline silicon wafers far better than the hydrogenation received during standard commercial firing conditions. Efficiency enhancements of up to 2% absolute are demonstrated on wafers with high dislocation densities. The impact of illumination to manipulate the charge state of hydrogen during annealing is investigated and found to not be significant on the wafers used in this study. This finding is contrary to a previous study on similar wafers that concluded increased H or H0 from laser illumination was responsible for the further passivation of positively charged dangling bonds within the dislocation clusters.

Mechanism of superlubricity of a DLC/Si_(3)N_(4) contact in the presence of castor oil and other green lubricants

To meet the surging needs in energy efficiency and eco-friendly lubricants,a novel superlubricious technology using a vegetable oil and ceramic materials is proposed.By coupling different hydrogen-free amorphous carbon coatings with varying fraction of sp^(2) and sp^(3) hybridized carbon in presence of a commercially available silicon nitride bulk ceramic,castor oil provides superlubricity although the liquid vegetable oil film in the contact is only a few nanometres thick at most.Besides a partial liquid film possibly separating surfaces in contact,local tribochemical reactions between asperities are essential to maintain superlubricity at low speeds.High local pressure activates chemical degradation of castor oil generating graphitic/graphenic-like species on top of asperities,thus helping both the chemical polishing of surface and its chemical passivation by H and OH species.Particularly,the formation of the formation of–(CH_(2)–CH_(2))n–noligomers have been evidenced to have a major role in the friction reduction.Computer simulation unveils that formation of chemical degradation products of castor oil on friction surfaces are favoured by the quantity of sp^(2)-hybridized carbon atoms in the amorphous carbon structure.Hence,tuning sp^(2)-carbon content in hydrogen-free amorphous carbon,in particular,on the top layers of the coating,provides an alternative way to control superlubricity achieved with castor oil and other selected green lubricants.