D263 Glass Research Articles

Wideband dielectric properties of silicon and glass substrates for terahertz integrated circuits and microsystems

This paper presents a comprehensive study of the optical and electrical dielectric material properties of six commonly-used silicon and glass substrates at terahertz (THz) frequencies, including refractive index, absorption coefficient, dielectric constant and loss factor. The material characterization techniques used in this paper feature THz time-domain transmission and reflection spectroscopy with the measurement frequencies from 0.5 THz up to a maximum of 6.5 THz. Of the six selected dielectric and semiconductor substrates, two are silicon wafers with resistivities ranging from 0.001 to 0.02 Ω-cm. From the measurement results, loss tangents of the selected silicon wafers range from 0.680 to 5.455 and the dielectric constants are from 1.079 to 17.735. The four other wafers are all glass-based substrates: D263 glass, Borofloat 33 glass, fused silica and Sapphire. From the measurements, it is found that the THz dielectric properties vary considerably between the substrate samples e.g. dielectric constants range from 1.925 to 3.207 while loss tangents are from 0.042 × 10−3 to 0.127. Most of the selected silicon and glass-based substrates are quite useful for many THz applications, e.g., THz integrated circuits (THz ICs), THz microsystem technologies (THz MSTs) and THz system-on-a-chip (THz SoC) and system-on-substrate (SiP).

Sputter deposition of PZT piezoelectric films on thin glass substrates for adjustable x-ray optics

Piezoelectric PbZr(0.52)Ti(0.48)O(3) (PZT) thin films deposited on thin glass substrates have been proposed for adjustable optics in future x-ray telescopes. The light weight of these x-ray optics enables large collecting areas, while the capability to correct mirror figure errors with the PZT thin film will allow much higher imaging resolution than possible with conventional lightweight optics. However, the low strain temperature and flexible nature of the thin glass complicate the use of chemical-solution deposition due to warping of the substrate at typical crystallization temperatures for the PZT. RF magnetron sputtering enabled preparation of PZT films with thicknesses up to 3 μm on Schott D263 glass substrates with much less deformation. X-ray diffraction analysis indicated that the films crystallized with the perovskite phase and showed no indication of secondary phases. Films with 1 cm(2) electrodes exhibited relative permittivity values near 1100 and loss tangents below 0.05. In addition, the remanent polarization was 26 μC/cm(2) with coercive fields of 33 kV/cm. The transverse piezoelectric coefficient was as high as -6.1±0.6 C/m(2). To assess influence functions for the x-ray optics application, the piezoelectrically induced deflection of individual cells was measured and compared with finite-element-analysis calculations. The good agreement between the results suggests that actuation of PZT thin films can control mirror figure errors to a precision of about 5 nm, allowing sub-arcsecond imaging.

Experimental testing and FEM simulation for thermal imprinting of micro/nano glass-optical devices

Thermal imprinting of glass-optical devices and its numerical simulation using the finite element method were investigated. The constitutive equation of the glass material was estimated using compression creep tests based on conventional thermoviscoelastic theory. The relaxation modulus of D263 glass was approximated by the generalized Maxwell model. For glass thermal imprinting, a glassy carbon die was used on which line and space or microlens array patterns were machined with a focused ion beam (FIB). The optimum molding-temperature condition that gives precise transcription profile was investigated in detail. Finite element analyses were performed to simulate the experimental glass thermal imprinting. In comparing experimental and numerical results, the transcription heights of groove or microlens obtained by experimental tests approximately agreed with numerical values. Finite element analyses using thermoviscoelastic property of glass are reliable in estimating suitable conditions for glass thermal imprinting.

The electrical properties of diamond-like carbon film/D263 glass composite for the substrate of micro-strip gas chamber

Micro-Strip Gas Chamber (MSGC) used as a position sensitive gas detector has perfect performances in the detection of X-ray, α particles, β particles, γ-ray and other nuclear irradiations. However, it encounters a severe problem, that is, positive charge accumulation which can be avoided by reducing the surface resistivity of insulating substrate. So, diamond-like carbon (DLC) film is deposited on D263 glass to modify its electrical properties as substrate for MSGC. DLC film has optical smoothness and strong adhesive force on D263 glass, which helps fabricate microelectrodes on it. Raman spectroscopy demonstrates that DLC film is of sp 3 and sp 2 bonds corresponding to the occupied bonding (σ) states and the empty antibonding (σ *) states, and therefore it is a type of electronically conducting material. I– V plots indicate that three samples enjoy very steady resistivities between 10 9 Ω cm and 10 12 Ω cm, especially the DLC film under high electrical field over 10 4 V cm −1, which meet the optimum requirements of MSGC. DLC film/D263 glass composite substrate is essential for MSGC to avoid charge-up.

Effect of radiation-induced substrate defects on microstrip gas chamber gain behaviour

The aim of this work was to quantify the influence of radiation-induced substrate defects on microstrip gas chamber (MSGC) gain behaviour. The first part of this paper focuses on radiation effects on a typical MSGC substrate: Desag D263 glass. Defect generation was studied for Desag D263 with pure silica (Suprasil 1) as a reference. We studied the evolution of defect concentration with respect to accumulated doses up to 480 kGy. Annealing studies of defects in Desag D263 were also performed. In the second part, the radiation sensitivity of Desag D263 glass has been linked to the behaviour of the detector under irradiation. Comparative gain measurements were taken before and after substrate irradiation at 10 and 80 kGy the minimal dose received during LHC operation and the dose for which defect density is maximum (respectively).

“Diamond” over-coated microstrip gas chambers for high rate operation

We describe recent developments on diamond-like carbon (DLC) over-coated Microstrip Gas Chambers made on boro-silicate drawn glass substrates. MSGC surface coating with thin DLC layer of stable and controlled resistivity was proposed to overcome the limitation of detector operation due to surface charging-up under avalanches. This brings also advantages for the detector manufacturing technology. The thin layer, deposited on top of a manufactured MSGC (over-coating), demonstrates excellent mechanical properties and very good stability. We report on recent measurements with DLC over-coated MSGCs of various surface resistivities (ranging from 10 1 Ω/□ to 10 16 Ω/□ on D-263 and AF45 glass substrates. Over-coated MSGCs with resistivity of the surface around 10 15 Ω/□ exhibit a stable charge gain up to radiation rates in excess of 10 6 Hz/mm 2 . Stable long-term operation up to 50 mC/cm of accumulated charge from avalanches has been demonstrated.

Recent advances in the construction and testing of MSGCs

We describe the assembly procedure and the operation in a high-intensity beam of a small but representative system of Micro Strip Gas Chambers (MSGC) fully equipped with readout electronics. The chambers, with an active area of 100 × 100 mm 2, are made on 300 μm diamond-like coated D-263 glass with 200 μm pitch gold or chromium strips. The readout electronics (PreMux 128) allows the recording of charge on individual anode strips. The monitoring task includes a complete control and characterization of each device before installation in the beam, such as measurement of surface resistivity, finding shorts, pulse height analysis, gas gain calibration, rate capability and testing of the final electronics. Preliminary results of the beam test are described.

The influence of polarization effects on an MSGC glass substrate

The effect of the polarization on Desag D263 glass has been tested by varying the gap between the anode and the cathode as well as the substrate thickness. A loss in gain as small as 1.5% could be obtained with a 10μm gap. We further determined that an admixture of 2% ethanol vapor led to an 8% deterioration of the energy resolution.