Arc discharge ion source for europium and other refractory metals implantation

Abstract

The best method for the impurity doping to the host material is the ion implantation. Due to high melting point of the rare earth standard metal ion sources are useless. One of the solution is to use chemical compounds of rare earths characterized by low melting point. In this paper we describe the novel design of the ion source suitable for refractory metal (e.g., rare earths) ion implantation. The dependencies of Eu(+) current on cathode and arc currents as well as on hydrogen flow are presented. Europium (III) chloride as the source of the europium atoms was used. Europium ions were produced during collisions of evaporated and decomposed EuCl(3) molecules with fast electrons. The typical current of the europium ion beam extracted from the ion source was 25 microA for the extraction voltage of 25 kV. The ion source works without maintenance breaks for approximately 50 h, which enables high dose implantation. The presented ion source needs neither advanced high power supplies nor high vacuum regime.

Plasma Ion Source with an Internal Evaporator

“…The shape of the anode makes the penetration of extraction field easier. Due to this (and small distance between the discharge and extraction hole) one may expect that the extracted currents could be larger than in the case of our earlier construction [12,13].…”

“…The arc discharge region, where ion production takes place, is as close as possible to the extraction opening. That factor could lead to the increase of extracted currents, compared to the cylindrical anode source [12,13]. Additionally, the front part of the source, being an anode, is negatively biased and attracts positive ions.…”

“…This approach was successfully applied in our previous design [12,13], combining features of Nielsen [3] and metal vapor arc discharge (MEVVA [14]) ion sources. The molybdenum crucible, often called an evaporator, is surrounded by a spiral cathode.…”

Chemical Composition of Native Oxide Layers on In+Implanted and Thermally Annealed GaAs

“…SI GaAs wafers were chemicaly cleaned before ion implantation [4]. They were irradiated with 250 keV In + ions using the UNIMAS ion implanter at Maria Curie-Skªodowska University [5]. The uence of implanted In + ions was 3 × 10 16 cm −2 at the ion current density below 1 µA cm −2 to avoid in situ annealing.…”

Thermal Desorption of Helium from Defected Silicon

“…Helium released from the sample was detected by the QMG220 quadruple mass spectrometer (Pfeiffer Vacuum, Asslar, Germany) controlled by the Quadera™ software. The boron doped 100-oriented silicon wafers were first implanted with Si + ions using the ion implanter in the Institute of Physics, Lublin, equipped with the versatile arc discharge ion source with the evaporator [15][16][17][18][19]. The implantation energy was 260 keV and the beam current density was maintained ≈1 µA/cm 2 .…”