Activation of Si implants into InAs characterized by Raman scattering

Abstract

Studies of implant activation in InAs have not been reported presumably because of challenges associated with junction leakage. The activation of 20 keV, Si þ implants into lightly doped (001) p-type bulk InAs performed at 100 C as a function of annealing time and temperature was measured via Raman scattering. Peak shift of the L þ coupled phonon-plasmon mode after annealing at 700 C shows that active n-type doping levels %5 Â 10 19 cm À3 are possible for ion implanted Si in InAs. These values are comparable to the highest reported active carrier concentrations of 8-12 Â 10 19 cm À3 for growth-doped n-InAs. Raman scattering is shown to be a viable, non-contact technique to measure active carrier concentration in instances where contact-based methods such as Hall effect produce erroneous measurements or junction leakage prevents the measurement of shallow n þ layers, which cannot be effectively isolated from the bulk. V C 2016 AIP Publishing LLC.

Phonon–Plasmon Coupling and Active Cu Dopants in Indium Arsenide Nanocrystals Studied by Resonance Raman Spectroscopy

“…45 A recent study on Si-doped bulk InAs used Raman scattering to identify the active dopants and free carrier concentration using scattering from the coupled L + phonon− plasmon mode. 57 In our data for the doped NCs, the changes in the relative intensities of the TO and LO modes are consistent with the above coupled phonon−plasmon picture. First, the Raman cross section for the LO mode is expected to weaken because of coupling to the plasmon oscillations.…”

“…Second, the increased Raman signal at the TO energy is in agreement with the appearance of the L − coupled mode, which at very high doping levels was measured to be very close in energy to the TO phonon. 45,57,58 The calculation in Figure 3 reveals that already at the level of a single active impurity per NC (marked by the right dashed black vertical line), the L − energy reaches the asymptotic value of the TO phonon energy. In our experiments we indeed observe a constant energy for the TO mode while its relative intensity increases upon doping.…”

“…However, even at very high doping levels the L + Raman cross section is very low, ∼20–30 times weaker than that of the L – , making it very difficult to detect using Raman scattering . A recent study on Si-doped bulk InAs used Raman scattering to identify the active dopants and free carrier concentration using scattering from the coupled L + phonon–plasmon mode …”