skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Hydrogen interaction kinetics of Ge dangling bonds at the Si{sub 0.25}Ge{sub 0.75}/SiO{sub 2} interface

Abstract

The hydrogen interaction kinetics of the GeP{sub b1} defect, previously identified by electron spin resonance (ESR) as an interfacial Ge dangling bond (DB) defect occurring in densities ∼7 × 10{sup 12} cm{sup −2} at the SiGe/SiO{sub 2} interfaces of condensation grown (100)Si/a-SiO{sub 2}/Ge{sub 0.75}Si{sub 0.25}/a-SiO{sub 2} structures, has been studied as function of temperature. This has been carried out, both in the isothermal and isochronal mode, through defect monitoring by capacitance-voltage measurements in conjunction with ESR probing, where it has previously been demonstrated the defects to operate as negative charge traps. The work entails a full interaction cycle study, comprised of analysis of both defect passivation (pictured as GeP{sub b1}-H formation) in molecular hydrogen (∼1 atm) and reactivation (GeP{sub b1}-H dissociation) in vacuum. It is found that both processes can be suitably described separately by the generalized simple thermal (GST) model, embodying a first order interaction kinetics description based on the basic chemical reactions GeP{sub b1} + H{sub 2} → GeP{sub b1}H + H and GeP{sub b1}H → GeP{sub b1} + H, which are found to be characterized by the average activation energies E{sub f} = 1.44 ± 0.04 eV and E{sub d} = 2.23 ± 0.04 eV, and attendant, assumedly Gaussian, spreads σE{sub f} = 0.20 ± 0.02 eV and σE{sub d} = 0.15 ± 0.02 eV, respectively. The substantial spreads refer to enhanced interfacial disorder. Combination of the separately inferred kinetic parametersmore » for passivation and dissociation results in the unified realistic GST description that incorporates the simultaneous competing action of passivation and dissociation, and which is found to excellently account for the full cycle data. For process times t{sub a} ∼ 35 min, it is found that even for the optimum treatment temperature ∼380 °C, only ∼60% of the GeP{sub b1} system can be electrically silenced, still far remote from device grade level. This ineffectiveness is concluded, for the major part, to be a direct consequence of the excessive spreads in the activation energies, ∼2–3 times larger than for the Si DB P{sub b} defects at the standard thermal (111)Si/SiO{sub 2} interface which may be easily passivated to device grade levels, strengthened by the reduced difference between the average E{sub f} and E{sub d} values. Exploring the guidelines of the GST model indicates that passivation can be improved by decreasing T{sub an} and attendant enlarging of t{sub a}, however, at best still leaving ∼2% defects unpassivated even for unrealistically extended anneal times. The average dissociation energy E{sub d} ∼ 2.23 eV, concluded as representing the GeP{sub b1}-H bond strength, is found to be smaller than the SiP{sub b}-H one, characterized by E{sub d} ∼ 2.83 eV. An energy deficiency is encountered regarding the energy sum rule inherent to the GST-model, the origin of which is substantiated to lie with a more complex nature of the forward passivation process than basically depicted in the GST model. The results are discussed within the context of theoretical considerations on the passivation of interfacial Ge DBs by hydrogen.« less

Authors:
; ;  [1]
  1. Semiconductor Physics Laboratory, Department of Physics and Astronomy, University of Leuven, 3001 Leuven (Belgium)
Publication Date:
OSTI Identifier:
22308559
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ACTIVATION ENERGY; CAPACITANCE; CRYSTAL DEFECTS; DISSOCIATION; DISSOCIATION ENERGY; ELECTRIC POTENTIAL; ELECTRON SPIN RESONANCE; GERMANIUM SILICIDES; HYDROGEN; INTERACTIONS; INTERFACES; PASSIVATION; RECOMMENDATIONS; REGENERATION; SILICON OXIDES; SUM RULES; TEMPERATURE DEPENDENCE; TRAPS

Citation Formats

Stesmans, A., E-mail: andre.stesmans@fys.kuleuven.be, Nguyen Hoang, T., and Afanas'ev, V. V.. Hydrogen interaction kinetics of Ge dangling bonds at the Si{sub 0.25}Ge{sub 0.75}/SiO{sub 2} interface. United States: N. p., 2014. Web. doi:10.1063/1.4880739.
Stesmans, A., E-mail: andre.stesmans@fys.kuleuven.be, Nguyen Hoang, T., & Afanas'ev, V. V.. Hydrogen interaction kinetics of Ge dangling bonds at the Si{sub 0.25}Ge{sub 0.75}/SiO{sub 2} interface. United States. doi:10.1063/1.4880739.
Stesmans, A., E-mail: andre.stesmans@fys.kuleuven.be, Nguyen Hoang, T., and Afanas'ev, V. V.. Mon . "Hydrogen interaction kinetics of Ge dangling bonds at the Si{sub 0.25}Ge{sub 0.75}/SiO{sub 2} interface". United States. doi:10.1063/1.4880739.
@article{osti_22308559,
title = {Hydrogen interaction kinetics of Ge dangling bonds at the Si{sub 0.25}Ge{sub 0.75}/SiO{sub 2} interface},
author = {Stesmans, A., E-mail: andre.stesmans@fys.kuleuven.be and Nguyen Hoang, T. and Afanas'ev, V. V.},
abstractNote = {The hydrogen interaction kinetics of the GeP{sub b1} defect, previously identified by electron spin resonance (ESR) as an interfacial Ge dangling bond (DB) defect occurring in densities ∼7 × 10{sup 12} cm{sup −2} at the SiGe/SiO{sub 2} interfaces of condensation grown (100)Si/a-SiO{sub 2}/Ge{sub 0.75}Si{sub 0.25}/a-SiO{sub 2} structures, has been studied as function of temperature. This has been carried out, both in the isothermal and isochronal mode, through defect monitoring by capacitance-voltage measurements in conjunction with ESR probing, where it has previously been demonstrated the defects to operate as negative charge traps. The work entails a full interaction cycle study, comprised of analysis of both defect passivation (pictured as GeP{sub b1}-H formation) in molecular hydrogen (∼1 atm) and reactivation (GeP{sub b1}-H dissociation) in vacuum. It is found that both processes can be suitably described separately by the generalized simple thermal (GST) model, embodying a first order interaction kinetics description based on the basic chemical reactions GeP{sub b1} + H{sub 2} → GeP{sub b1}H + H and GeP{sub b1}H → GeP{sub b1} + H, which are found to be characterized by the average activation energies E{sub f} = 1.44 ± 0.04 eV and E{sub d} = 2.23 ± 0.04 eV, and attendant, assumedly Gaussian, spreads σE{sub f} = 0.20 ± 0.02 eV and σE{sub d} = 0.15 ± 0.02 eV, respectively. The substantial spreads refer to enhanced interfacial disorder. Combination of the separately inferred kinetic parameters for passivation and dissociation results in the unified realistic GST description that incorporates the simultaneous competing action of passivation and dissociation, and which is found to excellently account for the full cycle data. For process times t{sub a} ∼ 35 min, it is found that even for the optimum treatment temperature ∼380 °C, only ∼60% of the GeP{sub b1} system can be electrically silenced, still far remote from device grade level. This ineffectiveness is concluded, for the major part, to be a direct consequence of the excessive spreads in the activation energies, ∼2–3 times larger than for the Si DB P{sub b} defects at the standard thermal (111)Si/SiO{sub 2} interface which may be easily passivated to device grade levels, strengthened by the reduced difference between the average E{sub f} and E{sub d} values. Exploring the guidelines of the GST model indicates that passivation can be improved by decreasing T{sub an} and attendant enlarging of t{sub a}, however, at best still leaving ∼2% defects unpassivated even for unrealistically extended anneal times. The average dissociation energy E{sub d} ∼ 2.23 eV, concluded as representing the GeP{sub b1}-H bond strength, is found to be smaller than the SiP{sub b}-H one, characterized by E{sub d} ∼ 2.83 eV. An energy deficiency is encountered regarding the energy sum rule inherent to the GST-model, the origin of which is substantiated to lie with a more complex nature of the forward passivation process than basically depicted in the GST model. The results are discussed within the context of theoretical considerations on the passivation of interfacial Ge DBs by hydrogen.},
doi = {10.1063/1.4880739},
journal = {Journal of Applied Physics},
number = 4,
volume = 116,
place = {United States},
year = {Mon Jul 28 00:00:00 EDT 2014},
month = {Mon Jul 28 00:00:00 EDT 2014}
}
  • In this paper a computational model is developed which allows one to calculate the contribution to the Zeeman linewidth arising from magnetic dipole-dipole interactions between unpaired electrons in the dilute limit, which in our specific application correspond to dangling bonds (P-italic/sub b-italic/ centers) localized at the (111) Si-SiO/sub 2/ interface. Transmission-electron-microscopy studies of the samples we studied with electron paramagnetic resonance (EPR) indicate that the interface between the silicon and the thermally grown oxide was chemically abrupt and atomically flat over distances ranging from 15 to 300 A-circle. The atomic flatness of the silicon ''surface'' at the interface was interruptedmore » by steps from one atomic (111) silicon plane to the next. Thus, the dangling bonds observed by EPR are believed to be essentially localized on a two-dimensional plane. The density of dangling bonds is between 3 x 10/sup 12/ and 5 x 10/sup 12/ cm/sup -2/, which suggests that resolved fine structure might be detectable as well as broadening of the P-italic/sub b-italic/ Zeeman resonance.« less
  • The effects of low temperature ([le]700 [degree]C ) annealing on the thermal dissociation of hydrogen-passivated interface trap centers of a SiO[sub 2]-Si(100) system is studied using positron annihilation spectroscopy. The Si---H bonds dissociate with an activation energy of 2.60[plus minus]0.06 eV. Assuming that the anneal generates trap centers with a single charge, positron measurements indicate that [similar to]4.5[times]10[sup 8] trap centers/cm[sup 2] are created by a 600 [degree]C anneal.
  • Short-period (Si{sub m}/Ge{sub n}){sub N} superlattices (SSLs) are grown step by step on a Si(001) substrates by solid source molecular beam epitaxy. Using the step-graded SSLs as buffer layers, 2000 Aa uniform Si{sub 0.75}Ge{sub 0.25} alloy layers are grown on the same substrates. The growth temperature of the SSLs and uniform layers is 500{degree}C. In the SSLs layers, m and n are the number of monolayers of Si and Ge, respectively. N is the period of (Si{sub m}/Ge{sub n}) bilayers. The samples grown are characterized by x-ray diffraction, atomic force microscopy (AFM), and transmission electron microscopy (TEM) as a functionmore » of the step number of SSL layers. The SSLs show very smooth surfaces [the root-mean-square (rms) surface roughness is between 7 and 12 Aa]. A dramatic decrease in roughness is observed in the uniform Si{sub 0.75}Ge{sub 0.25} alloy layers, when even a one-step SSL is used as a buffer layer. A noticeable increase in rms roughness is seen in both SSL and alloy layers when the number of Ge monolayers is changed from one to two. AFM observation shows that the rms surface roughness behavior of the SSLs is reflected to their corresponding top alloy layers. The residual strains in alloy layers are considerably lower, with a maximum relaxation rate of about 80% for the sample with a seven-step SSL buffer. Cross-sectional TEM images show that strained SSL buffer layers effectively deflect threading dislocations in the substrate or confine the dislocations in the SSL buffer layers. {copyright} 2001 American Institute of Physics.« less
  • Characterized herein are quantum-well Hall devices in Si-delta-doped Al{sub 0.25}Ga{sub 0.75}As/GaAs and pseudomorphic Al{sub 0.25}Ga{sub 0.75}As/In{sub 0.25}Ga{sub 0.75}As/GaAs heterostructures, grown by low-pressure metal organic chemical vapor deposition method. The Si-delta-doping technique has been applied to quantum-well Hall devices for the first time. As a result high electron mobilities of 8,100 cm{sup 2}/V {center_dot} s with a sheet electron density of 1.5 {times} 10{sup 12} cm{sup {minus}2} in Al{sub 0.25}Ga{sub 0.75}As/In{sub 0.25}Ga{sub 0.75}As/GaAs structure and of 6,000 cm{sup 2}/V {center_dot} s with the sheet electron density of 1.2 {times} 10{sup 12} cm{sup {minus}2} in Al{sub 0.25}Ga{sub 0.75}As/GaAs structure have been achievedmore » at room temperature, respectively. From Hall devices in Al{sub 0.25}Ga{sub 0.75}As/In{sub 0.25}Ga{sub 0.75}As/GaAs structure, the product sensitivity of 420 V/AT with temperature coefficient of {minus}0.015%/K has been obtained. This temperature characteristics is one of the best results reported. Additionally, a high signal-to-noise ratio corresponding to the minimum detectable magnetic field of 45 nT at 1 kHz and 75 nT at 100 Hz has been attained. These resolutions are among the best reported results.« less
  • Hydrogen is highly mobile in Si and vitreous SiO{sub 2}, and it reacts strongly with dangling bonds residing on Si and O atoms. These interactions have important consequences for metal-oxide- semiconductor structures, with noteworthy effects including the passivation of electrically active defects, mediation of radiation sensitivity, chemical passivation of etched Si surfaces, and still poorly understood effects on epitaxial growth from H-containing media. Despite the significance of these H reactions, fundamental understanding of them has remained seriously deficient; the H bonding energies have been known semiquantitatively at best, and the detailed reaction paths and rate-determining energetics of intermediate states havemore » remained largely speculative. We are addressing these issues through a coordinated program of experiment and theory with the goal of a unified, quantitatively predictive understanding. 3 figs.« less