Raman spectroscopic determination of hole concentration inundopedGaAsBi

Abstract

Raman spectra of undoped GaAs 1−x Bi x (0<x<0.037) grown on GaAs by molecular beam epitaxy were investigated. With an increase of Bi component, we find that the longitudinal optical phonon-hole-plasmon-coupled (LOPC) mode first appears in the vicinity of the unscreened longitudinal optical (ULO) phonon frequency, and then shifts towards the transverse optical (TO) phonon frequency. A new vibrational mode (∼287 cm −1 ) between the TO and the ULO phonons was verified by use of low temperature polarized Raman measurement and the corresponding scattering intensities are found to be linearly proportional to the composition of Bi in GaAsBi. The hole concentrations determined by using the LOPC/ULO Raman intensities ratio increase from ∼6.5×10 16 to ∼2.8×10 17 cm −3 with increased Bi content and the measured results are in agreement with Hall measurements. Furthermore, the influence of excitation laser power on the estimation of the hole densities is discussed with the help of power dependent Raman spectroscopy.

Raman scattering study on dilute nitride-bismide GaNAsBi alloys: behavior of photo-excited LO phonon-plasmon coupled mode

“…To fit the experimental spectra in the −z(Y, Y)z configuration, we assumed the existence of a new vibrational mode at ∼286 cm −1 (denoted by an asterisk), which has been observed in GaAsBi alloys. 16,17,38) As discussed in Ref. 38, this mode can be attributed to the disordered activated mode or Fröhlich mode.…”

“…Recently, Zhu et al estimated a lower native hole density in undoped GaAs 1−x Bi x (0% ⩽ x ⩽ 3.7%). 17) The calculated value increased from ∼6.5 × 10 16 to ∼2.8 × 10 17 cm −3 with increasing Bi composition. Moreover, they found that the hole density calculated using the LOPC mode increased monotonically with increasing excitation laser power.…”

“…13,14) Phonon-like damped LOPC modes were observed in previous Raman studies of ternary undoped GaAsBi alloys. [15][16][17] The observations of the strong damped LOPC modes have been explained by p-type conductivity of undoped GaAsBi evidenced by Hall measurements. 18) The p-type conductivity results from holes thermally excited into the valence band from the Bi-induced acceptor levels.…”

Investigation of the effects of GaAs substrate orientations on the electrical properties of sulfonated polyaniline based heterostructures

“…1. The intense peaks located at ~295 cm -1 and ~270 cm -1 are the unscreened longitudinal optical and transverse optical phonon modes of GaAs, respectively [17]. The spectrum exhibits several characteristic bands of the polyaniline (see inset in figure 1).…”

Structural and optical properties of n-type and p-type GaAs(1−x)Bi x thin films grown by molecular beam epitaxy on (311)B GaAs substrates

“…Depending on the laser power, the Raman spectra can have a significant contribution from photo-generated carriers [52][53][54][55][56][57][58], which can modify the LOPC modes due to intrinsic doping. Figure 4 shows typical Raman spectra of p-GaAs0.94Bi0.06 and n-GaAs samples, and in Fig.…”