| AVS 59th Annual International Symposium and Exhibition | |
| Applied Surface Science | Tuesday Sessions |
| Session AS-TuP |
| Session: | Applied Surface Science Poster Session |
| Presenter: | L. Chauhan, Dublin City University, Ireland |
| Authors: | L. Chauhan, Dublin City University, Ireland S. Gupta, Indian Institute of Science Bangalore, India P. Jaiswal, Indian Institute of Science Bangalore, India N. Bhat, Indian Institute of Science Bangalore, India S.A. Shivashankar, Indian Institute of Science Bangalore, India G.J. Hughes, Dublin City University, Ireland |
| Correspondent: | Click to Email |
High indium content InGaAs is a leading candidate for n-channel devices in future generations of complementary metal-oxide-semiconductor (CMOS) technology due to its high electron mobility and high saturation velocity. In recent years significant progress has been made in improving the electrical quality of the high-k dielectric InGaAs interface by the atomic layer deposition (ALD) of high-k materials on passivated surfaces. An additional technological issue which needs to be addressed for metal oxide semiconductor field effect transistors (MOSFETs) fabrication is the relatively high source/drain (S/D) contact resistance which results from poor dopant activation in III-V semiconductors. One proposed solution to this issue is to fabricate metal S/D Schottky-barrier MOSFET devices which requires control over the barrier height at the metal-InGaAs interface. It has recently been reported that the insertion of an ultrathin layer dielectric layer at the contact interface between the metal and the semiconductor can help in releasing the Fermi level to obtain a rectifying contact.
In this study we investigate the effectiveness of the insertion of an ultrathin ALD deposited Al2O3 dielectric layer on the Schottky barrier formed at the interface between the metal and the InGaAs. Schottky contacts were fabricated on 1nm and 2nm Al2O3 layers deposited on native oxide and sulphur passivated In0.53Ga0.47As for both n and p doped substrates. To investigate the dependence of Schottky barrier height (SBH) on metal work function (WF), both low (Al~4.30 eV) and high (Pt~5.65 eV) WF metals were deposited on these surface.
Rectifying behaviour was observed for the p-type substrates for the Al-InGaAs and Al/ Al2O3/InGaAs junctions and the SBH was measured to be ~0.60eV. Ohmic behaviour was observed on the Pt-InGaAs and Pt-Al2O3-InGaAs junctions regardless of the dielectric thickness. The Al2O3/InGaAs interfacial chemistry of these surfaces was investigated with x-ray photoelectron spectroscopy and no arsenic oxide was found on the Al2O3- native and sulphur treated InGaAs surfaces which suggests that on the native oxide InGaAs surface, Al2O3 depositionresulted in the consumption of the interfacial oxide.
Ohmic behaviour was observed on the all n-type metal/InGaAs and metal/Al2O3/InGaAs junctions regardless of the metal WF or thickness of the dielectric layer which suggests that the Fermi level is pinned near to the top of the conduction band for these InGaAs samples.