Fermi-level pinning and chemical structure of InP–metal interfaces

Brillson, L. J.; Brucker, C. F.; Katnani, A. D.; Stoffel, N. G.; Daniels, R. R.; Margaritondo, G.

doi:10.1116/1.571764

Cited by 95 publications

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“…2(b), produces interface states which exhibit a different spectral dependence on metal thickness, i.e., these interface states evolve faster with Cu versus Au thickness. This result is consistent with E F extracted from photoemission core level shifts for these interfaces, which showed 19 ness ranges. The 0.78-eV emission is a common feature between the Au and Cu/InP interfaces.…”

Section: Optical-emission Properties Of Interface States For Metals Osupporting

confidence: 90%

“…19 Thus, E F shifts slowly (rapidly) with Au (Cu) coverage^1 9 producing large n-type band bending with 10-20 A (2-4 A) deposition, which reduces NBG luminescence intensity at a corresponding rate. Al deposition produces relatively little band bending, 12,19 consistent with the NBG feature dominant after 20 A coverage. The NBG intensity reduction observed for Pd//>InP is also consistent with the large E F movement expected.…”

Section: Optical-emission Properties Of Interface States For Metals Omentioning

confidence: 99%

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Optical-Emission Properties of Interface States for Metals on III-V Semiconductor Compounds

1986

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We report the first study of optical-emission properties associated with interface-state formation for metals on III-V semiconductor surfaces. Cathodoluminescence spectroscopy reveals discrete levels distributed over a wide energy range and localized at the microscopic interface. Our results demonstrate the influence of the metal, the semiconductor, and its surface morphology on the energy distributions. Evolution of spectral features with interface formation, particularly above monolayer metal coverage, is correlated with Fermi-level movements and Schottky-barrier heights. PACS numbers: 78.60.Hk, 73.30. +y r 73.40.NsThe identification of interface states and their role in Schottky-barrier formation have long been key issues in the understanding of electronic properties of metal/ semiconductor (SC) junctions. 1 For clean, ordered InP or GaAs (110), intrinsic gap surface states are absent, and a few monolayers of deposited metal create new charge states which stabilize the Fermi level (E F ) in a limited range within the band gap. 2 Considerable spectroscopic evidence suggests that chemical effects (e.g., reaction and interdiffusion) take place concurrently which promote localized charge formation. Physical models for the localized charge states which influence metal/compound-SC contact rectification vary from gap states due to defects formed by metal atom condensation, 3 to metal-induced gap states defined by the SC band structure, 4 to chemisorption and charge transfer involving metals atoms and clusters, 5 to chemically formed dipole layers 6 and effective work functions of interface alloys. 7 Nevertheless, except for isolated absorption studies of surface and interface states by total internal reflection 8 or surface photovoltage spectroscopy 9 and near-edge photoluminescence of mechanically damaged surfaces, 10 the presence and energies of interface states have been inferred largely from measurements of capacitance, 1,11 current, 1,12 and E F movement 2 -5Here we report the most direct observation of metal/SC interface states thus far. We have detected luminescence from interface states by means of cathodoluminescence spectroscopy 13 (CLS), a technique common to bulk studies and recently applied to laserannealed metal/SC interfaces 14 and to GaAs/GaAlAs multilayer structures. 15 We have characterized the formation and evolution of interface states with metal deposition on ultrahigh-vacuum-cleaved (110) III-V SC surfaces of submonolayers up to several monolayers, where the metallic state of the overlayer is well defined. We show that dramatic changes are produced in the optical emission properties of III-V SC's upon metal deposition, both broad and discrete emission bands at energies below the band gap. Our studies reveal the influence of the particular metal, the SC, its morphology, and its bulk growth quality on the spectral distribution. Furthermore, the evolution of electron-excited optical emission spectra of metal/InP or GaAs interfaces shows qualitative differences at submonolayer versus multilayer meta...

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Section: Optical-emission Properties Of Interface States For Metals Osupporting

confidence: 90%

Section: Optical-emission Properties Of Interface States For Metals Omentioning

confidence: 99%

Optical-Emission Properties of Interface States for Metals on III-V Semiconductor Compounds

1986

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“…[12][13][14][15] In this context, it has been also reported that metal films which strongly react with the semiconductor anion give rise to small Schottky barrier heights. 14,15 The attempt of growing P-and In-free Fe films on S-passivated InP͑001͒ failed: 16 the S-terminated surface is disrupted upon Fe deposition, and, while the substrate InP͑001͒ core-level photoemission signal has been completely attenuated, the P, In, and, in addition, the S chemically shifted components of the spectra are clearly visible even for ordered Fe films.…”

Section: Introductionmentioning

confidence: 99%

Growth and magnetic properties of Fe films on InP(001)

2002

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An investigation of the InP͑001͒ surface and the characterization of thin Fe films grown on this substrate at Ϸ150 and Ϸ300 K are presented. As substrates, highly ordered P-rich (2ϫ4) reconstructed surfaces obtained by Ar ϩ ion bombardment at Ϸ570 K were used. The growth of Fe films in the submonolayer thickness range and the magnetic properties of thin Fe films grown on P-rich (2ϫ4) InP͑001͒ are reported. We observe a uniaxial in-plane magnetic anisotropy up to an Fe thickness of Ϸ14 monolayers, which is related to the uniaxial character of the InP͑001͒ reconstruction. From the magnetization behavior we obtained the surface/ interface contribution to the uniaxial anisotropy, and deduced that very small, if any, magnetically dead layers form at the interface. Auger electron spectroscopy data reveal that about one monolayer of In segregates to the top of the growing Fe film at Ϸ300 K, but does not support a strong Fe-InP͑001͒ intermixing, in contrast to the current belief. The current-voltage characterization of patterned Fe films grown on n-InP͑001͒ shows nonrectifying contacts at room temperature.

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“…If the work function of Cu (Φ M = 4.65 eV [11]) and the electron affinity of InP (χ S = 4.4 eV [12]) are considered, the Schottky-Mott relationship (Φ B = Φ M -χ S ) yields a barrier height of about 0.25 eV, which is much lower than the barrier height obtained from the I-V measurements. Fermi-level pinning at energies 0.4-0.5 eV below the conduction band edge of the n-type InP can lead to a barrier height as great as 0.5 eV [13]. A higher ideality factor than unity also implies the combined effect of the insulator layer and interface states [14].…”

Section: Methodsmentioning

confidence: 99%

Capacitance-Voltage (C-V) Characteristics of Cu/n-type InP Schottky Diodes

Kim¹

2016

Transactions on Electrical and Electronic Materials

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Using capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements, the electrical properties of Cu/ n-InP Schottky diodes were investigated. The values of C and G/ω were found to decrease with increasing frequency. The presence of interface states might cause excess capacitance, leading to frequency dispersion. The negative capacitance was observed under a forward bias voltage, which may be due to contact injection, interface states or minority-carrier injection. The barrier heights from C-V measurements were found to depend on the frequency. In particular, the barrier height at 200 kHz was found to be 0.65 eV, which was similar to the flat band barrier height of 0.66 eV.

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Fermi-level pinning and chemical structure of InP–metal interfaces

Cited by 95 publications

References 0 publications

Optical-Emission Properties of Interface States for Metals on III-V Semiconductor Compounds

Optical-Emission Properties of Interface States for Metals on III-V Semiconductor Compounds

Growth and magnetic properties of Fe films on InP(001)

Capacitance-Voltage (C-V) Characteristics of Cu/n-type InP Schottky Diodes

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