BEHAVIOR OF HYDROGEN-ATOMS IN BORON FILMS DURING H-2 AND HE GLOW-DISCHARGE AND THERMAL-DESORPTION

Hydrogen absorption and desorption characteristics in boron films depo sited on a graphite liner have been studied. The number of hydrogen at oms absorbed in the films is estimated from a decrease in hydrogen pre ssure during a hydrogen glow discharge. It was 1.9 x 10(17) atoms cm(2 ) in the 1 h discharge after an evacuation of H atoms contained in the original boron films by thermal desorption. Hydrogen atoms were absor bed continuously without saturation for 3 h during the discharge. The number of H atoms absorbed reached 2.6x10(17) atoms cm(2) at 3 h. A di scharge in helium was carried out to investigate H desorption characte ristics from hydrogen implanted boron films. It was verified that capa city for hydrogen absorption was recovered after the He discharge. Hyd rogen atoms were accumulated in the films by repetition of alternate H e and H-2 discharge. Thermal desorption experiments have been carried out by raising the liner temperature up to 500 degrees C for films aft er 1 h, 3 h hydrogen discharge and 6 times repetition of H-2/He discha rges. Most of the H atoms in the films were desorbed for all these cas es. The slow absorption process was confirmed through the thermal deso rption experiments. Copyright (C) 1996 Published by Elsevier Science L td.