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The plasma physics of dielectric barrier discharges (DBD) for carrying out ion implantation in insulators is investigated. A hollow cathode DBD excited by high-voltage pulses is suitable for ion bombardment of the surfaces of insulating tubing, porous material, particles and sheets. Plasma immersion ion implantation of insulating surfaces is useful for many applications in medicine and engineering. The ion bombardment of glass is useful for cleaning and surface modification. The ion implantation of polymers creates radicals that are able to bind molecules to their surfaces for applications in medical procedures and diagnostics. A wire diagnostic probe and optical emission spectroscopy are used for experimental work. A theory based on mutual capacitance is developed to convert data from the probe to give implanted charge as a function of pressure, voltage and pulse duration. We find the operating conditions that allow for charge to be implanted and those that achieve the highest implanted charge. [ABSTRACT FROM AUTHOR]

High-energy plasma immersion ion implantation (PIII) in the range of 50-100 keV is an interesting alternative of surface modification technique to more commonly investigated beam processing of materials in such energies. A stacked Blumlein (SB) technique was used to reach high-voltage pulses of 30 to 100 kV, with much cheaper and electronically simpler configuration compared to a hard-tube (HT) system previously used by another PIII group. The reason is because Blumlein systems employ cheaper thyratrons with higher current capabilities compared to HT tetrodes. Although HT modulators provide higher retained peak dose and variable pulse duration, Blumlein pulsers are preferable for low-cost systems with lower dose and high-energy implantation. The disadvantages of Blumlein systems are their fixed pulse duration and lower repetition rate (<300 Hz) during operation regime. In this paper, PIII results obtained for SB operations between 50 and 75 kV will be discussed using an improved vacuum system and a proper high-voltage feed-through of 75 kV. High-energy (up to 75 keV) short (1.2 µs) repetitive (100 Hz) pulses were delivered to produce the plasma and carry out nitrogen ion implantation in the high-voltage glow-discharge mode. Al7475, Al5052, Ti6Al4V alloys, and ultrahigh-molecular-weight polyethylene polymer are materials of great interest to the aerospace field which are being treated by this high-energy PIII technique. [ABSTRACT FROM AUTHOR]

A new method was developed to produce lithium plasma for plasma immersion ion implantation. Initially, an argon glow discharge with operation pressure ranging from 2 × 10-1 to 1 mbar is generated by negatively polarizing an electrode from -400 to -1500 V. Small pieces of metallic lithium that are 99.9% pure fill the top of a conic crucible, with a depth of 2 cm, in electric contact with the electrode. Argon ions from the plasma are used to bombard this target, where heat is created by the momentum transfer from the impacting ions to the crucible. By controlling the operation pressure and the electrode voltage polarization, it is possible to easily heat the crucible to temperatures above the lithium melting point (180 °C), causing its evaporation. Lithium atoms are then ionized, mainly due to collisions, with argon ions moving toward the crucible. Double Langmuir probe measurements indicated variation in the density of the discharge from 4 × 109 cm-3 to 1010 cm-3 after lithium evaporation. Silicon wafer pieces immersed in this mixed plasma were submitted to repetitive negative high-voltage pulses (3 kV/6 μs/2.5 kHz) to accelerate plasma ions. High strain in the treated layers was measured by high-resolution X-ray diffraction. Photoluminescence intensity increased after annealing. X-ray photoelectron spectrometry measurement revealed lithium implantation in silicon with an atomic concentration of 78% on the top surface and a penetration depth of about 75 nm. [ABSTRACT FROM AUTHOR]