Positron-induced ion-desorption spectroscopy has been constructed and used for measurements of positron-induced hydrogen ion desorption from Ni surfaces. The cross-section for proton desorption at a positron incident energy of 1.9 keV was larger than that at a positron incident energy of 2.9 keV. This value is larger than that for electron-stimulated desorption with similar incident energies, suggesting that ion desorption is caused by the thermalized positrons in the bulk.
Current–voltage (I
G–V
G) characteristics and green/red electroluminescence (EL) from metal–oxide–semiconductor (MOS) devices with indium–tin oxide (ITO)/[(Tb/Ba–Si–O)/(Tb/Eu–Si–O)] layers/n+-Si substrate are reported. The (Tb/Ba–Si–O) and (Tb/Eu–Si–O) layers were fabricated from the mixtures of organic liquid sources of (Tb+Ba) and (Tb+Eu), respectively, which were spin-coated on the n+-Si substrate and annealed at 850 °C for 30 min in air. I
G currents under EL emission correspond to Fowler–Nordheim (FN) tunnel current. The MOS devices with the (Tb/Ba)–Si–O layer and the (Tb/Eu)–Si–O layer emitted green and red EL, which originated from the intrashell transitions of 5D4–7F
J
(J = 6, 5, 4, and 3) of Tb3+ ions and 5D0–7F
J
(J = 1, 2, 3, and 4) of Eu3+ ions, respectively. EL intensity increased proportionally to I
G to the n-th power, where n was about 1.3, and the EL spectra were independent of the currents. The oxide layers on the Si substrate for the green and the red devices have the total thicknesses of about 40 and 30 nm, which consist of [Tb2O3 and (Tb/Ba–Si–O)] and [Tb2O3/Eu2O3 and (Tb/Eu–Si–O)] mixtures, respectively.
A device with Si rich gate oxide has attractive characteristics such as visible electroluminescence (EL) and current-voltage (I-V) hysteresis. Consequently, the MOS devices with Si-implanted SiO 2 have potentiality to integrate both the EL device and the high density Non-volatile memories on a single Si CMOS LSI chip [1,2]. Though visible EL from Si-implanted MOS capacitors have been reported [3,4], EL mechanisms and effects of process conditions still need further studies. In this work, spectrum analysis of EL from Si-implanted MOS capacitors is presented and effects of Si implantation and annealing conditions are discussed for EL mechanism. Fig. 1 gives a schematic cross section of a MOS capacitor with Si-implanted gate SiO 2 . The 30 nm thick thermal SiO 2 was grown on an n + -type (100) Si substrate of 0.02 cm (10 18 cm -3 ). Si ions were implanted into the SiO 2 , followed by N 2 annealing at 900 or 1000 °C for 30 min. The aluminum film was formed on the backside for ohmic contact. Finally, 15 nm thick Au film of 1.5 mm in diameter was sputter-deposited on the SiO 2 as a transparent electrode. Eight kinds of Siimplanted MOS capacitors and reference samples without implantation were fabricated as shown in Fig. 2. Similar I-V and C-V characteristics to the previous results are obtained [3,4]. The EL measurement system consists of a monochromator and a CCD camera cooled at -70 °C. The EL spectrum data were corrected for the total wavelength response curve of the system. EL spectra were measured under the constant gate currents (J G ) for the accumulation conditions. Fig. 3 shows measured EL spectra for n5b-L and n5b-H, which have different annealing temperature of 900 and 1000 °C, respectively. Both devices give similar and the highest peak at photon energy of about 2.7 eV (blue EL of 460 nm wavelength). The effect of annealing temperature on EL spectra is relatively small for the measured devices. Fig. 4(a) -(d) shows EL spectra for the devices implanted by the different energy and Si dose. The solid lines in Fig. 4 shows the calculated curves fitted by five Gaussian
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