Muonic atom as an acceptor centre in diamond

Abstract

Polarized negative muons were used to study the behaviour of the boron acceptor centre in synthetic diamond produced by the chemical vapour deposition (CVD) method. The negative muon substitutes one of the electrons in a carbon atom, and this muonic atom imitates the boron acceptor impurity in diamond. The temperature dependence of the muon spin relaxation rate and spin precession frequency were measured in the range of 20 − 330 K in a transverse magnetic field of 14 kOe. For the first time a negative shift of the muon spin precession was observed in diamond. It is tentatively attributed to an anisotropic hyperfine interaction in the boron acceptor.The magnetic measurements showed that the magnetic susceptibility of the CVD sample was close to that of the purest natural diamond.Diamond with its unsurpassed mechanical strength, thermal conductivity, and radiation hardness is a promising semiconductor for particle detectors and electronic components capable of withstanding high heat and radiation loads. Great advances have been made over the last years in the technology of manufacturing synthetic single crystal diamond and diamond films [1,2, 3].Boron is the only dopant which forms an acceptor centre (AC) in diamond with an ionization energy of ≈ 370 meV [4]. The metal-insulator transition occurs at a concentration of ≈ 2 · 10 20 cm −3 of boron atoms [5]. The EPR signal of boron impurities in diamond was observed only for uniaxially stressed samples [6], and the electronic state of this acceptor is investigated insufficiently.The possibility of using negative muons to study the behaviour of acceptor impurities in diamond arises from the fact that capture of a negative muon by a carbon atom results in the formation of a muonic atom µ B with an electron shell that is analogous to that of the boron atom. The evolution of the polarization of µ − in the 1s atomic state depends on the interaction of the muon spin with the electron shell of the muonic atom and on the interactions of this muonic atom 1

Evolution in Time of Radiation Defects Induced by Negative Pions and Muons in Crystals with a Diamond Structure

“…The possibility to extract valuable information about the hyperfine structure and interactions with a lattice of acceptor centers in different semiconductors with the help of negative muons was shown in the works [16][17][18][19]. Recently, µ − SRresearch of synthetic diamond crystals were carried out in [20][21][22][23]. We will examine evolution in time of radiation defects induced by negative muons in the following, taking in mind that they are the same for negative pions, as well.…”

Formation of chemically bound positively charged radiation defect induced by negative muon in diamond crystals

“…The recent experiments with negative muons in diamond [17][18][19] also show that the interpretation of the results cannot be performed convincingly under the assumption of a rapid (b 10 −10 s) thermalization of the forming muonic acceptor center μ B [20]. Thus, it appears actual to consider the thermalization process of a muonic acceptor center in crystals originating as a radiation-induced defect.…”