Pil Hyon Kim

100 keV focused ion beam system with a E×B mass filter for maskless ion implantation

Various liquid metal alloy ion sources and a 100 keV mass separated focused ion beam system have been fabricated and their basic characteristics have been measured. These are mass spectra, energy spread and angular current intensity for ion sources, and focusing characteristics of the system. It was observed that Be–Si–Au ternary alloy ion sources produce doubly charged Be and Si ions and the importance of these ion sources is demonstrated by fabricating a GaAs JFET using a maskless ion implantation technique and by PMMA resist exposure.

Flash Lamp Pumped Tunable Forsterite Laser

The flash lamp excited lasing of chromium doped forsterite (Cr:Mg2SiO4) was demonstrated for the first time. The maximum output was 4.95 mJ when the input energy was 283 J. The tuning range was from 1206 nm to 1250 nm.

30 nm Line Fabrication on PMMA Resist by Fine Focused Be Ion Beam

A 30 nm line pattern with 0.4 µm depth was successfully fabricated on a PMMA resist by a 100 kV focused Be++ beam emitted from Au–Si–Be ternary alloy ion source. The line width fabricated decreased with the decrease in ion dose.

200 kV Mass-Separated Fine Focused Ion Beam Apparatus

A 200 kV mass-separated focused ion beam apparatus using alloy liquid metal ion sources has been developed. Focusing characteristics have been estimated by scanning ion microscope images of the metal mesh and the sputter etching pattern fabricated by the focused ion beam. A beam diameter smaller than 80 nm was obtained for Ga+ with 100 pA at 200 kV.

Spectroscopic properties of Ti 3+ -doped BeAl 2 O 4

The crystallographic axis dependence of the absorption and photoluminescence spectra of Ti:BeAl2O4 is rationalized by assuming that the (3d)1 electron energy levels are split by the cubic and orthorhombic fields present at the Al site in chrysoberyl. The temperature dependence of the luminescence lifetime and integrated intensity indicates that the lifetime shortening that accompanies temperature increase is due to a nonradiative transition with an activation energy estimated to be 1770 cm−1.

Fabrication of Periodic Structures in GaAs by Focused-Ion-Beam Implantation

The characteristics of the ion bombardment-enhanced etching for a GaAs substrate using Ga focused-ion-beam implantation and selective etching of HCl have been investigated. The contrast and sensitivity of the etching as a positivetype resist were estimated to be 2.87 and 7.4×1013 cm-2, respectively. The microstructure of a 63 nm period was fabricated by the maskless process.

Passive Mode Locking of a Flashlamp-Pumped Ti:Sapphire Laser

Passive mode locking with a saturable absorber was observed in a flashlamp-pumped titanium-doped sapphire laser. The peak wavelength of the absorption spectrum of the saturable absorber (IR-125 dye) was almost the same as that of the gain spectrum of the titanium doped sapphire. The pulse durations of the mode-locked laser were about 100 ps.

Electron and Laser Beam Processing

Drilling of various materials by electron and laser beams has been studied with the purpose of comparing the two kinds of processing. The minimum spot obtainable with the electron beam is smaller than that with the laser beam. Hence a smaller hole can be perforated by the electron beam. But, in power efficiency, the laser beam is superior to the electron beam. When the two beams are allowed to impinge upon a metal work-piece, the surface power density of both beams is nearly of the same order, but a higher volume power density can be expected with the laser beam. These results are explained by the characteristics of the two beams.

40 nm Width Structure of GaAs Fabricated by Fine Focused Ion Beam Lithography and Chlorine Reactive Ion Etching

A 40 nm width structure of GaAs is fabricated by Be++ fine focused ion beam lithography and chlorine reactive ion etching using electron beam excited plasma (EBEP). The nanometer structure of the fabricated GaAs has a high aspect ratio of about 17 and a vertical side wall. It is found that the fabrication process has a high potential for nanometer microfabrication.

Flash-Lamp-Pumped Tunable Ti:BeAl2O4 Laser

The tunable lasing operation of Ti:BeAl2O4 was demonstrated by flash-lamp pumping for the first time. The maximum output energy of 21.1 mJ was obtained when the input energy was 283 J. The tuning range was from 753 nm to 946 nm.