(Invited) Surface Preparation and In/Ga Alloying Effects on InGaAs(001)-(2x4) Surfaces For ALD Gate Oxide Deposition

Abstract

High resolution STM images of In 0.53 Ga 0.47 As(001)-(2x4) were obtained and surface defects were quantified as a function of sample preparation technique.Published STM images of InGaAs(001)-(2x4) samples of varying In composition were examined and missing dimer unit cells, adatom trough defects, and incomplete atomic terraces were quantified for comparison with the In 0.53 Ga 0.47 As(001)-(2x4) surface. Density Functional Theory (DFT) modeling of α2(2x4) and β2(2x4) unit cell constructions and electronic structures show that the missing dimer defect creates conduction band edge states not readily passivated by trimethy aluminum; therefore, the density of dimer defects may cause trap state formation at oxide/InGaAs(001) interfaces.

(Invited) Rapid In-Situ Carbon and Oxygen Cleaning of In0.53Ga0.47As(001) and Si0.5Ge0.5(110) Surfaces via a H2 RF Downstream Plasma

“…Once the samples were loaded into the Omicron UHV VT-STM chamber with base pressure less than 1x10 -10 torr, they were degassed at 180°C for 30 minutes, decapped at 330-360 °C for 1 hour, and annealed to 380 °C in order to achieve the pure InGaAs(001)-(2x4) surface reconstruction. The (2x4) surface reconstruction was confirmed through low energy electron diffraction (LEED) measurements and STM images of the surface in a previous study (9).…”

Dual Passivation of Intrinsic Defects at the Compound Semiconductor/Oxide Interface Using an Oxidant and a Reductant

“…12 Details of the different unit cells are given in a previous study which has shown that In 0.27 Ga 0.73 As contains 42% missing dimer unit cells and In 0.53 Ga 0.47 As has 78%. 11 DFT simulations ( Figures 1À4) show that the defect unit cells cannot be fully passivated by TMA and require an oxidizing agent to suppress the remaining CB edge states. Two passivation experiments were performed to achieve dual passivation.…”

“…11 The R2-(2 Â 4) unit cell is missing an AsÀAs dimer on the row, which results in metallic InÀGa bonds. 12 The metalÀmetal bonds directly form valence band (VB) edge states and indirectly induce conduction band (CB) edge states; the metalÀmetal bonds generate bond angle strain in the edge As atoms which prefer to be in a tetrahedral sp 3 bonding configuration.…”

“…Edmonds et al showed that GaAs (2 Â 4) or InAs (2 Â 4) surfaces contain at least 8% R2-(2 Â 4) unit cells, and In 0.53 Ga 0.47 As contains 71% R2-(2 Â 4) unit cells, which accentuates the need to effectively passivate these defect unit cells. 11 The R2-(2 Â 4) unit cell is missing an AsÀAs dimer on the row, which results in metallic InÀGa bonds. 12 The metalÀmetal bonds directly form valence band (VB) edge states and indirectly induce conduction band (CB) edge Many passivation techniques have been explored for compound semiconductor surfaces, but most rely on external wet cleans, chemicals that are not ideal for introduction into commercial atomic layer deposition (ALD) tools, or temperatures that are not practical.…”

Dual passivation of GaAs (110) surfaces using O2/H2O and trimethylaluminum

“…5 This surface usually contains at least 42% defect unit cells which prevent efficient Fermi level modulation. 6 It may be possible to increase III-V based MOSFET drive current at low source-drain voltages by passivating the metallic In-Ga bonds and the strained As bonds which are present in the α2-(2 × 4) unit cells or by using a different crystallographic face, such as the (110) surface.…”