Diffusion and activation of n-type dopants in germanium

Abstract

The diffusion and activation of $n$-type impurities (P and As) implanted into $p$-type Ge(100) substrates were examined under various dose and annealing conditions. The secondary ion mass spectrometry profiles of chemical concentrations indicated the existence of a sufficiently high number of impurities with increasing implanted doses. However, spreading resistance probe profiles of electrical concentrations showed electrical concentration saturation in spite of increasing doses and indicated poor activation of As relative to P in Ge. The relationships between the chemical and electrical concentrations of P in Ge and Si were calculated, taking into account the effect of incomplete ionization. The results indicated that the activation of P was almost the same in Ge and Si. The activation ratios obtained experimentally were similar to the calculated values, implying insufficient degeneration of Ge. The profiles of P in Ge substrates with and without damage generated by Ge ion implantation were compared, and it was clarified that the damage that may compensate the activated $n$-type dopants has no relationship with the activation of P in Ge.Comment: 6 pages, 4 figure

The formation, stability, and suitability of n-type junctions in germanium formed by solid phase epitaxial recrystallization

“…[6][7][8][9] Quantifying the expected diffusion is difficult as available diffusivity values were either extracted under intrinsic conditions, or at higher temperatures than studied here. 1 However, extrapolating diffusivity values from Chui et al, 6 which are accurate for high concentrations, only a few nanometers of diffusion could be expected for the highest thermal budgets in this work.…”

“…n-type dopants in germanium have proven to be problematic, and are now a key bottleneck in the realization of advanced n-type MOS ͑NMOS͒ device performance and scaling. 5 In short, phosphorus ͑P͒ and arsenic ͑As͒ are relatively difficult to activate and diffuse quickly, [6][7][8][9] leading to high resistances and limited capability to reduce the device dimensions.…”

A Study on Contact Resistance Reduction in Ni Germanide/Ge using Sb Interlayer

“…However Ge CMOS has several issues. One is the difficulty for forming highly doped n-type Ge owing to its high diffusivity and low solubility [2]. And the other is the Fermi level pinning of metal near the charge neutrality level, close to the valence band maximum of germanium [3][4][5].…”

Effects of Carbon Pre-Germanidation Implantation on the Thermal Stability of NiGe and Dopant Segregation on Both n- and p-Type Ge Substrate

“…Especially, despite excellent performance for Ge p-MOSFETs has been achieved, 35 the fabrication of high performance Ge n-MOSFETs is still struggling because of high diffusivity and low activation concentration of n-type dopants such as P in Ge. 36 It is well known that carbon plays a very important role in forming n-type ultra-shallow junction, as well as to enhance the active doping concentration in that it can prevent the rapid diffusion of P by forming PV − clusters. 37 Besides, the incorporation of carbon can also z E-mail: luojun@ime.ac.cn effectively suppress the diffusion of B by forming carbon-interstitials (C-I) pairs.…”