Non-metastable recombination induced reactions involving hydrogen in SiC

2004 ◽  
Vol 813 ◽  
Author(s):  
Yaroslav Koshka ◽  
Bharat Krishnan ◽  
Michael S. Mazzola
Keyword(s):  
Energy Gap ◽  
Hole Concentration ◽  
Optical Excitation ◽  
Electrical Measurements ◽  
Free Hole ◽  
Defect Complexes ◽  
Conductivity Type ◽  
Defect Reactions ◽  
Range Migration ◽  
P Type

ABSTRACTA brief survey of some of the recent results of recombination-induced defect reactions involving hydrogen in 4H and 6H-SiC is given. A variety of outcomes of such reactions have been observed in hydrogenated 4H and 6H-SiC polytypes under optical excitation at reduced temperature. A few different non-metastable hydrogen-defect complexes can form, including hydrogen complexes with Al and B acceptors, hydrogen complex with Si vacancy, as well as some other non-identified complexes. Electrical measurements indicated strong recombination-induced passivation of the electrical activity of aluminum and boron acceptors in SiC. This passivation resulted in the reduction of the net free hole concentration and even inversion of the conductivity type. It is suggested that optical excitation causes a long-range migration of hydrogen followed by its capture in one or another kind of defect complexes. Further insight in the formation of specific complexes as a result of recombination-induced defect reactions is provided by thermal admittance spectroscopy. Energy gap levels in the regions that remained p-type after hydrogenation as well as in the regions where the conductivity was inverted by the recombination-induced passivation are investigated.

GROWTH AND CHARACTERIZATION OF p-Type GaAs LAYERS USING ATOMIC HYDROGEN AS A REAGENT

2001 ◽  
Vol 15 (17n19) ◽  
pp. 809-812 ◽  
Author(s):  
F. SILVA-ANDRADE ◽  
F. CHÁVEZ ◽  
F. TENORIO ◽  
N. MORALES ◽  
J. I. BECERRA PONCE DE LEON ◽  
...  
Keyword(s):  
Vapor Deposition ◽  
Atomic Hydrogen ◽  
Hole Concentration ◽  
Chemical Vapor ◽  
Conductivity Type ◽  
Technological Field ◽  
Vapor Deposition Technique ◽  
P Type ◽  
Residual Impurities

Atomic hydrogen has been found to have a great number of useful applications in the technological field of semiconducting materials. It has been used as a reagent in the epitaxial growth processes to control the incorporation of residual impurities. Atomic hydrogen can react with GaAs thus producing Ga- and As- hydrogen volatile species in controlled conditions. The atomic hydrogen can be produced in a chemical vapor deposition chamber using a hot tungsten filament. In this work we report the results of a study on GaAs layers grown using the close space vapor deposition technique with atomic hydrogen as a reagent. The conductivity type of the grown layers is closely related to the conductivity type of the GaAs source. We have grown p-type GaAs layers with l×1018 cm-3 hole concentration using GaAs sources with the same acceptor concentration. 10 K photoluminesence measurements were nlade on the source and the epitaxial GaAs layers. The PL spectra revealed that the residual impurities in the GaAs layers were originated from the source. The mirror like appearance of the grown layers as well as their electrical and optical characteristics demonstrate they can be used in the manufacture of GaAs semiconductor devices.

The study of HgCdTe MBE-grown structure with ion milling

2010 ◽  
Vol 18 (3) ◽  
Author(s):  
M.M. Pociask
Keyword(s):  
Molecular Beam ◽  
Ion Milling ◽  
Type Conversion ◽  
Defect Complexes ◽  
Conductivity Type ◽  
Equilibrium Processes ◽  
Before And After ◽  
P Type ◽  
Grown Structure

AbstractOf many techniques used to characterize quality of HgCdTe, ion milling is emerging as a unique means to reveal electrically active and neutral defects and complexes. Ion milling is capable of strongly affecting electrical properties of HgCdTe, up to conductivity type conversion in p-type material. It appears, that strongly non-equilibrium processes which take place under ion milling, when material is oversaturated with mercury interstitial atoms generated near a surface, lead to formation of specific defect complexes, which may not form under other type of treatment. By measuring parameters of a crystal before and after milling, and following disintegration of defects with time after ion milling (’relaxation’), one can detect and identify these defects. This method was applied to analyse different samples grown by molecular beam epitaxy.

scholarly journals Определение концентрации свободных носителей заряда в легированных бором кремниевых нанонитях при помощи инфракрасной спектроскопии в режиме нарушенного полного внутреннего отражения

2019 ◽  
Vol 53 (11) ◽  
pp. 1557
Author(s):  
Е.А. Липкова ◽  
А.И. Ефимова ◽  
К.А. Гончар ◽  
Д.Е. Преснов ◽  
А.А. Елисеев ◽  
...  
Keyword(s):  
Silicon Nanowires ◽  
Annealing Temperature ◽  
Hole Concentration ◽  
Free Charge Carrier ◽  
Transverse Dimension ◽  
Charge Carrier Concentration ◽  
Attenuated Total Reflection ◽  
Free Charge ◽  
Free Hole ◽  
P Type

Attenuated total reflection infrared spectroscopy was used to determine the free charge carrier concentration in the arrays of silicon nanowires of characteristic transverse dimension of 50–100 nm and the length of the order of 10 μm which were formed on low-doped crystalline p-type silicon via metal-stimulated chemical etching and subjected to additional thermodiffusion boron doping at the temperatures 850–1000 оС. It was found out that the free hole concentration varies from 5•1018 to 3•1019 cm-3 depending on the annealing temperature and reaches it’s maximum at 900–950 оС. The results can be used to expand the scope of silicon nanowires application in photonics, sensorics and thermoelectric power converters.

Epitaxial Growth and Properties of Mg-Doped Gan Film Produced by Atmospheric Mocvd System With Three Layered Lammar Flow Gas Injection

1997 ◽  
Vol 482 ◽  
Author(s):  
N. Akutsu ◽  
H. Tokunaga ◽  
I. Waki ◽  
A. Yamaguchi ◽  
K. Matsumoto
Keyword(s):  
Thermal Annealing ◽  
Room Temperature ◽  
Hole Concentration ◽  
Gas Injection ◽  
Chemical Vapor ◽  
Free Hole ◽  
Mg Doping ◽  
Doping Effects ◽  
P Type ◽  
Mg Doped

AbstractMg-doped GaN films with a variety of Mg concentrations were grown on sapphire (0001) by horizontal atmospheric metalorganic chemical vapor deposition (MOCVD) system with three layered laminar flow gas injection in an attempt to study the Mg doping effects on film quality. The increase of Mg concentration induced an increase of x-ray rocking curve full width at half maximum (FWHM) and degradation of surface morphology. Secondary ion mass spectroscopy (SIMS) analysis shows increase of Si and O, associated with Mg-doping concentration. Si and O concentrations of Mg-doped film are up to 5×1016cm−3 and 5×1017cm−3 at Mg concentration of 4.5×1019cm−3, respectively. Strong 380nm emission and weak 430nm emission were observed by photoluminescence (PL) measurement at room temperature for as-grown Mg-doped GaN films which shows p-type conductivity after thermal annealing. While, in highliy Mg-doped GaN films which do not show the p-type conduction after thermal annealing, 430nm and/or 450nm emission were dominating. The highest room temperature free hole concentration achieved was p=2.5× 1018cm−3 with mobility μp=l.9cm2/V s.

scholarly journals Substrate and Mg doping effects in GaAs nanowires

2017 ◽  
Vol 8 ◽  
pp. 2126-2138 ◽  
Author(s):  
Perumal Kannappan ◽  
Nabiha Ben Sedrine ◽  
Jennifer P Teixeira ◽  
Maria R Soares ◽  
Bruno P Falcão ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electronic Structure ◽  
Field Effect Transistors ◽  
Hole Concentration ◽  
Optical Measurements ◽  
Back Gate ◽  
Free Hole ◽  
Mg Doping ◽  
Gaas Nanowires ◽  
P Type

Mg doping of GaAs nanowires has been established as a viable alternative to Be doping in order to achieve p-type electrical conductivity. Although reports on the optical properties are available, few reports exist about the physical properties of intermediate-to-high Mg doping in GaAs nanowires grown by molecular beam epitaxy (MBE) on GaAs(111)B and Si(111) substrates. In this work, we address this topic and present further understanding on the fundamental aspects. As the Mg doping was increased, structural and optical investigations revealed: i) a lower influence of the polytypic nature of the GaAs nanowires on their electronic structure; ii) a considerable reduction of the density of vertical nanowires, which is almost null for growth on Si(111); iii) the occurrence of a higher WZ phase fraction, in particular for growth on Si(111); iv) an increase of the activation energy to release the less bound carrier in the radiative state from nanowires grown on GaAs(111)B; and v) a higher influence of defects on the activation of nonradiative de-excitation channels in the case of nanowires only grown on Si(111). Back-gate field effect transistors were fabricated with individual nanowires and the p-type electrical conductivity was measured with free hole concentration ranging from 2.7 × 1016 cm−3 to 1.4 × 1017 cm−3. The estimated electrical mobility was in the range ≈0.3–39 cm2 /Vs and the dominant scattering mechanism is ascribed to the WZ/ZB interfaces. Electrical and optical measurements showed a lower influence of the polytypic structure of the nanowires on their electronic structure. The involvement of Mg in one of the radiative transitions observed for growth on the Si(111) substrate is suggested.

The Effect of Doping Concentration and Conductivity Type on Preferential Etching of 4H-SiC by Molten KOH

2004 ◽  
Vol 815 ◽  
Author(s):  
Ying Gao ◽  
Zehong Zhang ◽  
Robert Bondokov ◽  
Stanislav Soloviev ◽  
Tangali Sudarshan
Keyword(s):  
Thermal Diffusion ◽  
Basal Plane ◽  
Doping Concentration ◽  
Structural Defects ◽  
Etch Pits ◽  
Conductivity Type ◽  
Isotropic Etching ◽  
Electrochemical Processes ◽  
P Type ◽  
Koh Etching

AbstractMolten KOH etchings were implemented to delineate structural defects in the n- and ptype 4H-SiC samples with different doping concentrations. It was observed that the etch preference is significantly influenced by both the doping concentrations and the conductivity types. The p-type Si-face 4H-SiC substrate has the most preferential etching property, while it is least for n+ samples. It has been clearly demonstrated that the molten KOH etching process involves both chemical and electrochemical processes, during which isotropic etching and preferential etching are competitive. The n+ 4H-SiC substrate was overcompensated via thermal diffusion of boron to p-type and followed by molten KOH etching. Three kinds of etch pits corresponding to threading screw, threading edge, and basal plane dislocations are distinguishably revealed. The same approach was also successfully employed in delineating structural defects in (0001) C-face SiC wafers.

scholarly journals The Effects of Amorphous Layer Regrowth on Carbon Activation in GaAs and InP

1993 ◽  
Vol 316 ◽  
Author(s):  
A.J. Moll ◽  
J.W. Ager ◽  
K.M. Yu ◽  
W. Walukiewicz ◽  
E.E. Haller
Keyword(s):  
Hole Concentration ◽  
Amorphous Layer ◽  
Free Hole ◽  
Initial Results

ABSTRACTThe effect of the Ga dose on the activation of implanted carbon in GaAs is determined. The free hole concentration is found to depend on the depth of the amorphous layer created by the Ga co-implant. Initial results on C implantation in InP indicate the behavior of C is very different in InP when compared to GaAs. The role of precipitation in reducing the activation of C in both GaAs and InP is discussed.

Defect Complexes and Non-Equilibrium Processes Underlying the P-Type Doping of GaN

1998 ◽  
Vol 537 ◽  
Author(s):  
Fernando A. Reboredo ◽  
Sokrates T. Pantelides
Keyword(s):  
High Temperature ◽  
Experimental Evidence ◽  
First Principles ◽  
Final Anneal ◽  
First Principles Calculations ◽  
Defect Complexes ◽  
Equilibrium Processes ◽  
Open Questions ◽  
High Temperature Anneal ◽  
P Type

AbstractIt is well known that hydrogen plays a key role in p-type doping of GaN. It is believed that H passivates substitutional Mg during growth by forming a Mgs-N-Hi complex; in subsequent annealing, H is removed, resulting in p-type doping. Several open questions have remained, however, such as experimental evidence for other complexes involving Mg and H and difficulties in accounting for the relatively high-temperature anneal needed to remove H. We present first principles calculations in terms of which we show that the doping process is in fact significantly more complex. In particular, interstitial Mg plays a major role in limiting p-type doping. Overall, several substitutional/interstitial complexes form and can bind H, with vibrational frequencies that account for hitherto unidentified observed lines. We predict that these defects, which limit doping efficiency, can be eliminated by annealing in an atmosphere of H and N prior to the final anneal that removes H.

ION CHANNELING AND PIXE STUDIES OF S IMPLANTATION IN GaAs

1992 ◽  
Vol 02 (02) ◽  
pp. 151-159
Author(s):  
LIU SHIJIE ◽  
WANG JIANG ◽  
HU ZAOHUEI ◽  
XIA ZHONGHUONG ◽  
GAO ZHIGIANG ◽  
...  
Keyword(s):  
Room Temperature ◽  
Dislocation Loops ◽  
Good Recovery ◽  
Electrical Measurements ◽  
X Ray ◽  
Defect Complexes ◽  
Ion Channeling ◽  
Transmission Electron ◽  
Activation Efficiency ◽  
Very High

GaAs (100) crystals were implanted with 100 keV S+ to a dose of 3×1015 cm−2 in a nonchanneling direction at room temperature, and treated with rapid thermal annealing (RTA). He+ Rutherford backscattering and particle-induced X-ray emission in channeling mode in combination with transmission electron microscopy (TEM) were used to study the damage and the lattice location of S atoms. It is revealed that the RTA at 950 °C for 10 sec has resulted in a very good recovery of crystallinity with a few residual defects in the form of dislocation loops, and a very high substitutionality (~90%). The activation efficiency and the Hall mobility of the implanted samples are found to be low after the electrical measurements. Based on these results an extended dopant diffusion effect for the residual defects and a correlation between the electrical properties and defect complexes are suggested.

An effective and efficient approach to p-type AlN by Be2:O codoping from first-principles calculations

2016 ◽  
Vol 30 (20) ◽  
pp. 1650257
Author(s):  
Meng Zhao ◽  
Wenjun Wang ◽  
Jun Wang ◽  
Junwei Yang ◽  
Weijie Hu ◽  
...  
Keyword(s):  
First Principles ◽  
Ionization Energy ◽  
Hole Concentration ◽  
Valence Band Maximum ◽  
First Principles Calculations ◽  
Mutual Compensation ◽  
Efficient Approach ◽  
P Type ◽  
Codoping Method

Various Be:O-codoped AlN crystals have been investigated via first-principles calculations to evaluate the role of the different combinations in effectively and efficiently inducing p-type carriers. It is found that the O atom is favored to bond with two Be atoms. The formed Be2:O complexes decrease the acceptor ionization energy to 0.11 eV, which is 0.16 eV lower than that of an isolated Be in AlN, implying that the hole concentration could probably be increased by 2–3 orders of magnitude. The electronic structure of Be2:O-codoped AlN shows that the lower ionization energy can be attributed to the interaction between Be and O. The Be–O complexes, despite failing to induce p-type carriers for the mutual compensation of Be and O, introduce new occupied states on the valence-band maximum (VBM) and hence the energy needed for the transition of electrons to the acceptor level is reduced. Thus, the Be2:O codoping method is expected to be an effective and efficient approach to realizing p-type AlN.

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