Fluorine effect on As diffusion in Ge

Abstract

The enhanced diffusion of donor atoms, via a vacancy (V)-mechanism, severely affects the realization of ultrahigh doped regions in miniaturized germanium (Ge) based devices. In this work, we report a study about the effect of fluorine (F) on the diffusion of arsenic (As) in Ge and give insights on the physical mechanisms involved. With these aims we employed experiments in Ge co-implanted with F and As and density functional theory calculations. We demonstrate that the implantation of F enriches the Ge matrix in V, causing an enhanced diffusion of As within the layer amorphized by F and As implantation and subsequently regrown by solid phase epitaxy. Next to the end-of-range damaged region F forms complexes with Ge interstitials, that act as sinks for V and induce an abrupt suppression of As diffusion. The interaction of Ge interstitials with fluorine interstitials is confirmed by theoretical calculations. Finally, we prove that a possible F-As chemical interaction does not play any significant role on dopant diffusion. These results can be applied to realize abrupt ultra-shallow n-type doped regions in future generation of Ge-based devices.

Electrical compensation via vacancy–donor complexes in arsenic-implanted and laser-annealed germanium

“…5 The latter has been associated with a vacancy-mediated diffusion mechanism, 6 as opposed to Si, wherein donors diffuse through both vacancies (V's) and interstitials. 7 Furthermore, donor passivation is known to be a problem in Ge, and it has been attributed to the formation of vacancy-donor ðV M -D N Þ complexes in a few experimental [8][9][10][11] and computational 12 studies. In a recent positron study on highly n-type Ge obtained by diffusion doping, an extensive formation of V-D N complexes was found with the common donors D 2 {As, P, Sb}.…”

Doping and cluster formation in diamond

“…Typically, to overcome doping difficulties in semiconductors codoping strategies are employed. [19][20][21] In diamond, a popular codoping strategy is the formation of donor-acceptor clusters. [22][23][24] By the clusters the solubility of desirable doping atoms can be enhanced (via the Coulomb coupling between the donor and acceptor), whereas the defect level concentration can be reduced (via the donor and acceptor level repulsion).…”

Isovalent doping and the CiOi defect in germanium

“…For decades the characteristic dimensions of devices were reduced and this has constituted the importance of point defects and defect clusters increasingly important as they can impact materials properties. Examples include the need to reduce the concentration of vacancy-oxygen pairs (VO or A-centers) and/or the carbon-related defects (such as C i O i (Si I ) n , n = 1, 2,…) in Si [13][14][15][16][17][18][19] and the requirement to contain the fast n-type dopant diffusion in Ge [2,10,12].…”

“…Although germanium (Ge) was implemented in the first transistor commencing the solid state electronics era silicon (Si) prevailed for applications in microelectronics, photovoltaics and sensors for many decades due to its high quality crystal growth technology and advantageous native oxide [1][2][3][4][5][6][7][8][9][10][11][12]. In the past few years materials with advantageous physical properties (e.g.…”

“…In the past few years materials with advantageous physical properties (e.g. higher carrier mobilities, low dopant activation temperatures and smaller band-gap) such as germanium (Ge) are becoming increasingly important [1][2][3][4][5][6][7][8][9][10][11][12]. The consideration of alternative substrates is mainly due to the high-k gate dielectric materials, which have effectively eliminated the requirement of a good quality native oxide in advanced nanoelectronic devices [1].…”