~ Pergamon Solid State Communications, Vol. 93, No. 5, pp. 425-430, 1995 Elsevier Science Ltd Printed in Great Britain 0038-1098(94)00811-6 0038-1098/95 $9.50+.00 HYDROGEN PASSIVATION OF Cd ACCEPTORS IN III-V SEMICONDUCTORS STUDIED BY PAC SPECTROSCOPY Doris Forkel-Wirth l, N. Achtziger 1, A. Burchard 2, J.C. Correia 4,5, M. Deicher 2 T. Licht t, R. Magerle 2, J.G. Marques 4, j. Meier I, W. Pfeiffer 2, U. Reislthner 3, M. Riib 1, M. Toulemonde 5, W. Witthuhn 3 and the 1SOLDE Collaboration 5 I) Physikalisches Institut, Universitdt Erlangen-Niirnberg, D-91058 Erlangen, FRG, 2) Fakultdt ffir Physik, Universitdt Konstanz, D-78434 Konstanz, FRG, 3) Physikalische Fakultdt, Universitdt Jena, D-07743 Jena, FRG, 4) Centro de Fisica Nuclear da Universidade de Lisboa, Portugal 5) CERN / PPE, Ct1-121 l Geneva 23, Switzerland Formation, structure, and stability of hydrogen correlated complexes, created at Cd ac- ceptors in GaP, InP, and InAs have been studied after plasma charging as well as after H + and / or He + implantation at different energies. The different complexes were moni- tored by the perturbed angular correlation technique (PAC). In lnP and GaP, the stabil- ity of Cd-H pairs is very similar for comparable Cd concentrations (ED = 1.4(2) eV and E D = 1.5(1) eV). In InAs, two different hydrogen correlated configurations are ob- served, one could be identified as Cd-H pair, oriented in <111> lattice direction (VQ = 427 MHz, ~ = 0). The second complex involves at least one H atom and radiation de- fects or, favoured by a defect induced, secondary mechanism several hydrogen atoms. Keywords: A. semiconductors, C. impurities in semiconductors, C. point defects, D. radiation effects, E. X-ray and "/-ray spectroscopies Introduction Hydrogen interacts with electrically active impurities in semiconductors and the scientific interest in H passiva- tion mechanism has considerably grown 1,2. But due to the complex behaviour of H, not all relevant parameters are yet known for Si, and for III-V compounds even less in- formation is available 2. Triggered by the importance of this topic, in the late 80s the first perturbed angular corre- lation (PAC) spectroscopy experiments have been per- formed to study H in III-V compounds 3. During the last few years a considerable amount of new information could 425 be provided concerning formation and stability of acceptor- hydrogen complexes, using Cd as a typical "representative" of group IIB metal acceptors. It was found that Cd-H pairs in GaAs, InP, and GaP are formed after plasma charging or low energy H ÷ implantation 4-7, whereas in InAs and InSb hydrogen correlated complexes have been observed after plasma charging 4. The crystallographic orientation and the stability of the Cd-H pairs support a model proposed by Pajot 8 which favours H on the bond center site, forming H-P and H-As bonds instead of an acceptor-hydrogen bond. In addition, a second hydrogen correlated Cd- complex was found in plasma charged GaAs and InAs 4.9,