A model for Fermi-level pinning in semiconductors: radiation defects, interface boundaries

Brudnyi, V. N.; Grinyaev, S. N.; Kolin, N. G.

doi:10.1016/j.physb.2003.11.092

Cited by 52 publications

(39 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A feature of the InAs semiconductor is that radiation defects shift the Fermi level toward the conduction band, which leads to an increase of the carrier concentration in the n-type material or the p-n type conversion in p-InAs (Ref. [18]). …”

Section: Gaasmentioning

confidence: 99%

Anomalous Hall effect in two-phase semiconductor structures: The role of ferromagnetic inclusions

et al. 2014

View full text Add to dashboard Cite

The Hall effect in InMnAs layers with MnAs inclusions of 20-50 nm in size is studied both theoretically and experimentally. We find that the anomalous Hall effect can be explained by the Lorentz force caused by the magnetic field of ferromagnetic inclusions and by an inhomogeneous distribution of the current density in the layer. The hysteretic dependence of the average magnetization of ferromagnetic inclusions on an external magnetic field results in a hysteretic dependence of RH(Hext). Thus we show the possibility of a hysteretic RH(Hext) dependence (i.e. observation of the anomalous Hall effect) in thin conductive layers with ferromagnetic inclusions in the absence of carriers spin polarization.PACS numbers: 61.72.uj, 72.20.My, 75.50.Pp The investigation of the anomalous Hall effect (AHE) is a widely used experimental method for the diagnostics of the magnetic and transport properties of ferromagnetic layers, in particular, those of diluted magnetic semiconductors (DMS) [1]. In the conventional interpretation, the AHE is a consequence of an asymmetric scattering of spin-polarized charge carriers in ferromagnetic materials [2]. Thus the observation of the AHE is traditionally considered to be a proof of the presence of spin-polarized carriers. The spin polarization of carriers in DMS is usually attributed to a mechanism of indirect exchange interaction between transition metal ions via charge carriers [3,4]. In the high temperature region this mechanism should become slack [3,4]. However, the AHE was observed at room temperature or above in some Mn-doped semiconductors [5][6][7]. The AHE was also observed at about 300 K in Co-doped TiO 2 [8,9] and (La,Sr)TiO 3 [10] layers containing Co clusters. In Refs. [8-10] the appearance of AHE was related to spin polarization by extrinsic (induced by the clusters) spin orbit scattering. Earlier, it was also observed that in InMnAs layers obtained by laser deposition in gas atmosphere a clear hysteresis in the magnetic field dependencies of the Hall resistance manifests itself up to room temperature [11].In III-Mn-V layers the second-phase inclusions may appear during technology processes. In particular, nanosize ferromagnetic MnAs particles can be embedded in a semiconductor matrix [12,13] In this Letter, we present the results of theoretical and experimental investigations of the AHE in the InMnAs layers obtained by laser deposition. Nevertheless our results can be generalized to other conductive layers with ferromagnetic inclusions. Figure 1 shows the brightfield cross-sectional scanning transmission electron microscopy (STEM) image of the InMnAs/GaAs structure with Y Mn =0.2. The image reveals a phase inhomogeneity of the InMnAs layer. Figure 1 also shows the energydispersive X-ray spectroscopy (EDS) mapping of Mn, In and As in the structure. The bright areas in the Mn mapping image correspond to the regions of predominantly Mn atoms. At the same time these regions are free from In atoms. Taking into account the uniform distribution of As atoms it can be concluded ...

show abstract

Section: Gaasmentioning

confidence: 99%

Anomalous Hall effect in two-phase semiconductor structures: The role of ferromagnetic inclusions

et al. 2014

View full text Add to dashboard Cite

show abstract

“…It is shown that within the whole range of the w-Al x Ga 1-x N compositions, the CNL is located in the upper half of the band gap, which results in the n-type conductivity of this material upon exposure to high-energy radiation.The concept of local charge electroneutrality (the "neutral" point) is widely used for analyzing energy-level diagrams of unstressed interfaces, estimating electrophysical characteristics of defect semiconductors, and calculating equilibrium levels of doping materials by chemical impurities [1][2][3][4][5][6][7]. The charge electroneutrality level acts as a fundamental crystal parameter identical for all isotype semiconductors with similar type of chemical bonds.…”

mentioning

confidence: 99%

The charge neutrality level in w-AlxGa1−x N solid solutions

2006

View full text Add to dashboard Cite

537.311.322Energy positions of the charge electroneutrality level (CNL) and neutral vacancy levels of nitrogen are calculated for w-GaN, w-AlN, and w-Al x Ga 1-x N versus solid-solution composition x in the virtual-crystal approximation. It is shown that within the whole range of the w-Al x Ga 1-x N compositions, the CNL is located in the upper half of the band gap, which results in the n-type conductivity of this material upon exposure to high-energy radiation.The concept of local charge electroneutrality (the "neutral" point) is widely used for analyzing energy-level diagrams of unstressed interfaces, estimating electrophysical characteristics of defect semiconductors, and calculating equilibrium levels of doping materials by chemical impurities [1][2][3][4][5][6][7]. The charge electroneutrality level acts as a fundamental crystal parameter identical for all isotype semiconductors with similar type of chemical bonds. Thus, within a unified concept, we can obtain the most important parameters of interfaces (Schottky-barrier height and band discontinuities in semiconductor heteropairs), calculate the electrophysical properties (conductivity type, limiting Fermi level, and specific-resistance rate) of defect semiconductor materials upon exposure to high-energy radiation or severe plastic deformation, and estimate the limiting equilibrium levels of semiconductor doping by hydrogen-like (shallow) chemical impurities. That is why this problem currently attracts considerable attention.In recent years, the group A 3 N nitrides including solid solutions and heterostructures on their basis are of great interest as candidate materials for rf electronics and semiconductor optics. However, the practical use of these compounds is limited by the high concentration of growth defects, mainly in the nitrogen sublattice (~10 19 cm -3 ), caused by high synthesis temperatures and volatility of the nitrogen components. The exposure to high-energy radiation is known to change the electron characteristics of materials (conductivity type, specific-resistance rate, and Fermi-level position) due to the formation of defect states in the band gap of the semiconductor crystal. This is widely used in radiation technology to control electrophysical, optical, recombination, and other properties of semiconductors. These studies are of great importance for investigations into tolerance of semiconductor materials and devices to high-energy radiation. Hence, studying the intrinsic lattice defects and their influence on the properties of wide-band A 3 N group nitrides is one of the most topical problems of materials science and technology.In this work, the energy dependence of the local charge electroneutrality level in w-GaN, w-AlN, and solid solutions on their bases is studied using the calculation methods we developed earlier. The correlation between the CNL position and the energy positions of neutral vacancy levels for nitrogen (neutral nitrogen vacancy is one of the major growth defects in these compounds) is analyzed.The band structure of w...

show abstract

“…These show that if the radiation-induced defects are introduced into InSb, the Fermi level is shifted to a position in the lower part of the band gap corresponding to the charge neutrality level of the crystal defect states (E cnl ) [12], to the level of a local amphoteric defect (E lnl ) [12], to the midgap between the conduction and valence bands of the crystal averaged over the first Brillouin zone (<E G >/2) [12], and to the level of the deepest crystal defect (E dl ) in the energy range in the vicinity of its band gap [13]. The calculated values of E g , E cnl , E lnl , E dl , and <E G >/2 in InSb shown in Table 2 qualitatively support this assumption despite their wide scatter caused by the narrow InSb band gap and stringent requirements on the accuracy of calculations.…”

Section: Before Irradiationmentioning

confidence: 99%

“…Table 1 and Figures 1 and 2 show the electrophysical parameters of the InSb microcrystals measured before and after irradiation by various integral electron flows. It is seen that the high-temperature (Т ≈ 300 К) irradiation of n-InSb by 13 MeV electrons results in a decrease in the free-electron concentration and mobility within the whole range of initial doping levels under study. In so doing, the efficiency of radiation-induced acceptors increases with increasing the initial …”

mentioning

confidence: 94%

Effect of electron irradiation on InSb microcrystals

Bolshakova¹,

Makido²,

Maslyuk

et al. 2006

Russ Phys J

View full text Add to dashboard Cite

The results of experimental studies of electrophysical properties of heavily doped n-InSb whiskers exposed to electron irradiation (13 MeV, 300 К) are reported. The limiting electrophysical parameters and the problem of the Fermi-level pinning in irradiated InSb are discussed.The radiation-induced defects (RD) in InSb irradiated by electrons are usually studied in the bulk InSb single crystals [1][2][3]. It should be noted that despite of a great body of available experimental data, the information on the nature of radiation-induced defects and their influence on the electrophysical parameters of InSb is rather contradictory due to a number of reasons. Since the free electron concentration in InSb is about n i ≈ 2⋅10 16 cm -3 at room temperatures, the radiation-induced defects are usually studied at low temperatures. In addition, the investigations of RDs in InSb are hampered by the narrow band gap E g ≅ 0.24 eV and low free-electron effective mass m n (Г 6с ) ≅ 0.014m 0 , since these promote formation of the electron-density tails in the InSb band gap and occurrence of hopping conductivity in the samples compensated by irradiation. Therefore, use is made of an extra-pure or weakly doped material, for which low irradiation doses are required [4]. However, the main current commercial use of InSb is the production of Hall generators (HG) operating at room temperatures. In addition, in certain conditions of application (in nuclear physics or in space), the stability of HGs to high-energy radiation should be provided [5,6], generating a need for investigations into the RDs in heavily doped n-InSb at temperatures close to 300 K.In this work, we report on the results of experimental studies of filamentary n-InSb microcrystals (whiskers) doped by the amphoteric impurity Sn up to the free electron concentration n 0 = (5.7·10 16 -1.4·10 18 ) cm -3 during the growth process. Whiskers are known to have a perfect structure and a low concentration of growth defects in comparison with bulk materials. However, the radiation-induced defects in the electron irradiated InSb whiskers have not been studied up to date. The amphoteric impurity Sn is widely used for doping n-InSb to obtain the material with various free electron concentrations. In this case, this impurity can be distributed both in the In and Sb sublattices during doping. The Sn atoms occupy mainly the In sites in a weakly doped material. With increasing the doping level, the Sn atoms begin to effectively redistribute between the In and Sb sublattices to form the neutral Sn In -Sn Sb pairs, and this results in an increase in the compensation factor of the heavily doped material. The compensation factor is K = N(Sn Sb )/N(Sn In ) ∼ 0.2 at n 0 ∼ 10 16 cm -3 and it increases up to the value of K ~ 1 at the limiting doping levels N Sn ∼ (3-4)·10 20 cm -3 and free-electron concentrations n 0 ∼ (3-4)·10 18 cm -3 [7,8]. The behavior of this highly compensated material exposed to high-energy radiation fields is also of great scientific interest.The electrophysical parameters ...

show abstract

A model for Fermi-level pinning in semiconductors: radiation defects, interface boundaries

Cited by 52 publications

References 27 publications

Anomalous Hall effect in two-phase semiconductor structures: The role of ferromagnetic inclusions

Anomalous Hall effect in two-phase semiconductor structures: The role of ferromagnetic inclusions

The charge neutrality level in w-AlxGa1−x N solid solutions

Effect of electron irradiation on InSb microcrystals

Contact Info

Product

Resources

About