THERMAL-DESORPTION OF DEUTERIUM IMPLANTED INTO BERYLLIUM

By means of TDS measurements it is shown that the desorption of deuter ium from Be implanted with 5 keV D-ions to fluences, Phi, from 1 x 10( 20) D/m(2) to 1 x 10(21) D/m(2) proceeds in one high-temperature stage B, while at Phi x 1.2 x 10(21) D/m(2) one more stage A appears. The d esorption maximum A is narrow and consists of two peaks A(1) and A(2) at about 460 K and 490 K, respectively. Peak A(1) is attributed to the desorption of deuterium from the walls of opened channels formed unde r D-ion implantation. Peak A(2) is a consequence of the opening of a p art of bubbles/closed channels to the outer surface. The position of m aximum B, T-m(B), shifts noticeably and nonsteadily on the fluence in a range 850-1050 K. The origin of this maximum is the liberation of D- atoms bound at vacancy complexes discussed previously by Wampler. The dependence of T-m(B) on the fluence is governed by the interaction of freely migrating D-atoms with arrangements of fully closed or partly o pened gas cavities which are created under temperature ramping, but di fferently in specimens implanted with D-ions to different fluences.