Surface Fermi level pinning in epitaxial InSb studied by electric-field-induced Raman scattering

Abstract

Electric-field-induced Raman scattering by longitudinal optical (LO) phonons has been used to study the surface Fermi level position in InSb layers grown by molecular beam epitaxy on (100) GaAs. From the analysis of a variety of layers it is found that the LO phonon scattering intensity, relative to that of intrinsic two-LO phonon scattering, decreases with increasing optical power density in n-type samples, but remains constant in p-type and undoped layers, which are residual p type. The power dependence of the relative LO phonon intensity for n-type doping is shown to be caused by a surface electric field, the strength of which is reduced upon increasing illumination due to screening by photogenerated carriers. As this effect is only found in n-type layers, we conclude that the surface Fermi level is pinned at the valence band thus giving rise to a sizeable surface electric field in n-type but not in p-type material.

Monolithic InSb nanostructure photodetectors on Si using rapid melt growth

“…Previously, Fermi level pinning at the valence band edge was observed in n-type InSb, giving rise to a sizeable surface electric field under dark conditions. 32 Van der Pauw and Hall measurements on RMG InSb (Fig. S2 in ESI † ) confirms that the material is n-type like in our previous work 33 and we thus expect the band structure to resemble the schematic in Fig.…”

Synthesis and properties of antimonide nanowires

“…The fact that InSb FETs currently do not show advantages over InAs FETs may be related to their surface Fermi level pinning and the Schottky barrier height at the contacts: it is established that the Fermi level in InAs typically pins in the conduction band, facilitating the formation of low-resistive contacts [105]. InSb on the other hand typically exhibits Fermi level pinning close to the valence band, thus leading to the formation of Schottky barriers at the contacts [106]. The surface depletion layer may lead to a lower carrier concentration in the nanowires as well as a higher contact resistance.…”

Indium Antimonide Nanowires: Synthesis and Properties

“…It is noticed that in InAs-based FETs, Fermi level pins into conduction band which results in negligible small resistance [ 158 ]. On the other hand, InSb NWs typically show pinning of Fermi level close to the valence band as a result Schottky barriers develop at the contacts [ 159 ].…”