Raman scattering study of surface barriers in GaAs passivated in alcoholic sulfide solutions

Abstract

Raman scattering has been used to study the variation of surface barriers in GaAs due to sulfur passivation in solutions of ammonium sulfide [(NH4)2S] in different alcohols (ethanol, isopropanol, and tert-butanol). It has been found that the surface barrier height and the depletion layer width decrease considerably with the decrease of the dielectric constant of the passivating solution.

Effect of surface treatment with different sulfide solutions on the ultrafast dynamics of photogenerated carriers in GaAs(1 0 0)

“…Moreover, the treatment with the aqueous sulfide solution has very little effect on surface recombination velocity in n-GaAs(100). These data are in a good agreement with the previous results of photoluminescence and Raman scattering study of n-GaAs(100) passivated with aqueous and alcoholic solutions of ammonium sulfide [27,28]. In particular, it was found that after the treatment of GaAs(100) surface with aqueous sulfide solution the photoluminescence intensity increases, whereas the surface depletion layer width that characterizes the density of the occupied surface states remains unchanged [28].…”

Passivation at semiconductor/electrolyte interface: Role of adsorbate solvation and reactivity in surface atomic and electronic structure modification of III–V semiconductor

“…Spectra were taken in a backscattering geometry allowing both longitudinal (LO) and coupled phonon-plasmon mode scattering to be observed [30]. Raman scattering studies were performed on wafers of n-GaAs(1 0 0) [N D = 1 Â 10 18 cm À3 ] and p-GaAs(1 0 0) [N A = 1 Â 10 18 cm À3 ], which prior to adsorption of HS À ions were etched in HCl for 100 s at room temperature to remove native oxide layer [6,7]. The corresponding surface depletion layer width for these semiconductors were d n0 = 33.6 nm and d p0 = 26.9 nm, respectively, i.e., considerably lower than the penetration depth of laser excitation into GaAs.…”

“…the semiconductor surface (surface recombination velocity, depletion layer width) as a function of the dielectric constant and molecular properties of the solvents [5][6][7]. It is well known that the solute-solvent interaction can affect the valence shell of the solvated ion [8], the reaction pathway [9], and the properties of chemical bonds formed in the solution [10].…”

Improved electrical properties of wafer-bonded p-GaAs/n-InP interfaces with sulfide passivation

“…Surface treatments for III-V compound semiconductor wafers by sulfide compounds were shown to enhance the photoluminescence response and improve the electrical properties by removing the oxygen on the surfaces and reducing the surface trap state densities. [13][14][15][16][17][18] Although this well-known technique has never been employed for direct bonded interfaces, this study shows that the wafers with residual sulfur atoms can be directly bonded without decreasing the bonding strength at the interfaces. In addition, sulfide-passivated interfaces give a significant improvement of the interfacial electrical conductivities and direct bonding of heavily doped p-GaAs and n-InP wafers after sulfide passivation forms a tunnel diode at temperatures as low as 300°C.…”