avs 2012 poster v3 (final version)

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  • Interfacial properties of atomic layer deposited TiO2 films on InAs (100) surfaces

    ALD of TiO2 on etched InAs surfaces

    Conclusions

    Native oxide consumption is verified during ALD of TiO2 on InAs (100)

    surfaces.

    In oxides bubble to surface of TiO2 films during the deposition.

    Native oxide consumption rate increases as deposition temperature is

    raised during the deposition of TiO2 on InAs (100) and GaAs (100)

    surfaces.

    NSF CAREER award (DMR-0846445)

    Materials and Devices for Information Technology (MDITR) STC

    (DMR-0120967)

    Dr. Karen Gaskell (UMD) for taking the XPS data

    ALD of TiO2 on native oxide InAs surfaces

    Liwang Ye, Theodosia Gougousi Department of Physics , UMBC

    Practically sharp interface is obtained after the deposition of TiO2 on HF

    and NH4OH etched InAs (100) surfaces

    The deposition of high- dielectrics on III-V semiconductors has been under intensive

    study due to its potential applications in metal-oxide-semiconductor field-effect

    transistors (MOSFET). The interface plays an important role in improving the

    performance of the semiconductor devices. Consumption of native oxides has been

    demonstrated for Atomic Layer Deposition (ALD) of metal oxides on III-V substrates

    when amide precursors are used. In this work we investigate the deposition and

    interfacial properties of TiO2 on InAs.

    UMBC UMBC

    Temperature dependence of the

    native oxide consumption

    Starting surfaces: HF or NH4OH etched InAs (100) surfaces.

    Deposition Temperature: 200C

    TiO2 film thickness: ~2.2 nm

    Starting surfaces: Degreased native oxide InAs (100) surfaces.

    Deposition Temperature: 100~250C

    Precursors: Tetrakis dimethyl amino titanium (TDMATi) and H2O

    Starting surfaces: Degreased native oxide InAs (100) surfaces

    Deposition temperature: 200C

    Native oxides are consumed gradually.

    In oxides bubble to the surface of the TiO2 films.

    46 44 42 40

    As-In

    AsOx

    As2O3As2O5

    As 3d

    20 19 18 17 16 15

    In 4d

    In-AsIn2O3

    In2Ox

    152 148 144 140 136

    As 3p

    As2O3

    As2O5

    As-In

    AsOx

    448 447 446 445 444 443 442

    In-As

    In-O

    In 3d5/2

    Inte

    ns

    ity

    Binding energy (eV)

    Starting

    surface

    100C

    150C

    200C

    250C

    ALD of ~2nm TiO2 on InAs (100) surfaces

    ALD of ~3nm TiO2 on InAs (100) surfaces

    Native oxide consumption rate increases as deposition temperature is

    raised.

    At 250C As oxides are almost completely removed; some In oxide left.

    ~ 1.6 nm

    native oxide

    InAs

    epoxy

    TiO2 ~4.3nm

    InAs

    epoxy

    Inte

    nsit

    y

    starting surface after the deposition

    HRTEM of ~4.3nm TiO2 on native oxide InAs (100) surfaces

    448 447 446 445 444 443

    In-AsIn-O

    In 3d5/2

    24 22 20 18 16 14

    In 4d

    In-AsIn2OxIn2O3

    O2s

    45 40 35 30

    As 3d

    As-InAs2O3As2O5

    Ti 3p

    152 148 144 140 136

    As 3p

    As-InAs2O3

    As2O5

    Sta

    rting

    su

    rfac

    es

    ~

    2.0

    nm

    TiO

    2

    ~3.7

    nm

    TiO

    2

    ~6.4

    nm

    TiO

    2

    ~3.0

    nm

    TiO

    2

    ~6.4

    nm

    TiO

    2

    Sp

    utte

    red

    Inte

    ns

    ity

    Binding energy (eV)

    Native oxide evolution during TiO2 deposition

    Introduction

    Formation of a practically sharp interface is verified by HRTEM.

    Substrate

    Native oxide

    TiO2

    (a) (b) (c) (d)

    (a)Starting surface: native oxide covered InAs (100) surface

    (b)During the deposition: both As and In oxides are consumed gradually;

    In oxides diffuse gradually through the TiO2 film and accumulate on its

    surface.

    (c) Interface is almost free of native oxides. Some In oxides remain on

    the topmost layer of the TiO2 film.

    (d)Remaining surface In oxides are removed by sputtering.

    Starting surfaces: Degreased native oxide GaAs (100) surfaces

    Deposition temperature: 100~250C

    ~2nm TiO2 on GaAs ~3nm TiO2 on GaAs

    ALD of TiO2 on GaAs (100) surfaces

    Native oxide consumption rate increases as deposition temperature is

    raised.

    At 250C As oxides are almost complete removed; some Ga oxide left.

    Acknowledgements

    45 40 35

    As 3d

    As2O5

    As2O3

    As-In

    Ti 3p

    448 447 446 445 444 443

    In-O

    In-As

    In 3d5/2

    24 22 20 18 16 14

    In 4d

    In2O3

    In2Ox

    In-As

    O 2s

    HF

    etc

    he

    d

    + 2

    .2 n

    m T

    iO2

    As

    rec

    eiv

    ed

    InA

    s (1

    00

    ) N

    H4 O

    H e

    tch

    ed

    + 2

    .2 n

    m T

    iO2

    Binding energy (eV)

    Inte

    nsit

    y

    152 148 144 140 136

    As 3p

    As-InAs2O3

    As2O5

    48 46 44 42 40

    As 3d

    As2O5 As2O3

    As-Ga

    AsOx

    22 21 20 19 18

    Ga-AsGa2O

    Ga2O3

    Ga 3d

    46 44 42 40

    As 3d

    As2O5 As2O3AsOx

    As-Ga

    Inte

    ns

    ity

    Binding energy (eV)

    100C

    150C

    200C

    250C

    22 21 20 19 18

    Ga-AsGa2OGa2O3

    Ga 3d

    Starting

    surface

    46 44 42 40

    As2O5As2O3

    AsOx

    As-In

    As 3d

    152 148 144 140 136

    As 3p

    As2O5

    As2O3As-In

    AsOx

    447 446 445 444 443 442

    In-AsIn-O

    In 3d5/2

    20 19 18 17 16 15

    In 4d

    In2O3

    In2Ox

    In-As

    Binding energy (eV)

    100C

    150C

    200C

    250C

    Starting

    surface