Control of conduction type in Al- and N-codoped ZnO thin films

Yuan, Guodong; Ye, Z. Z.; Zhu, Liping; Qian, Qi; Zhao, Binghui; Fan, Rong; Perkins, Craig L.; Zhang, Shou-Cheng

doi:10.1063/1.1928318

Cited by 85 publications

(36 citation statements)

References 20 publications

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“…The traditional co-doping approach 9 by doping donor and acceptor simultaneously is another way to enhance the solubility of a dopant in ZnO. There have been several publications reporting on successful fabrication of codoped p-type ZnO 5, [10][11][12][13][14][15][16] , as well as failures [17][18][19] . However, the high ionization energy of acceptors, caused by the very low valence band maximum (VBM) of ZnO, is hard to overcome 20 .…”

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confidence: 99%

Design of shallow acceptors in ZnO through early transition metals codoped with N acceptors

et al. 2011

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We perform first-principles density-functional theory calculations to study the atomic and electronic properties of early transition metals (Zr, Ti, Y, and Sc) co-doped with N in wurtzite ZnO. By incorporating early transition metals Ti, Zr, Y and Sc with N into ZnO simultaneously, we find that forming complexes (Zr-2N), (Ti-2N), (Y-N) and (Sc-N) induces fully occupied impurity bands with the N 2p character above the valence band maximum of host ZnO. With further doping of N in ZnO, the systems (Zr-2N):N, (Ti-2N):N, (Y-N):N or (Sc-N):N have acceptor ionization energies lower than that of the isolated N acceptor in ZnO. Under different growth conditions (i.e using N2O or NO source for the nitrogen atoms), we calculate the formation energies of the defect complexes and compare the dopability of the selected co-doped systems. Our results show that the valence band maximum characteristic of ZnO can be altered by compensated donor-acceptor pairs, thus improve the p-type dopability.

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confidence: 99%

Design of shallow acceptors in ZnO through early transition metals codoped with N acceptors

et al. 2011

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Tunable n‐Type Conductivity and Transport Properties of Ga‐doped ZnO Nanowire Arrays

et al. 2007

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As an important II-VI semiconductor, ZnO has attracted increasing interests owing to its unique properties such as wide band-gap (3.37 eV) and large exciton binding energy (60 meV).[1] ZnO has shown great potential in optoelectronic devices such as light emitting diodes (LED) and laser diodes (LDs) operating in the short-wavelength or UV region.[2]Compared to their thin-film counterparts, [3][4] nanoscale devices assembled on free-standing nanowires [5][6][7][8][9][10] could enable new functions, high efficiency, enhanced performance, and diverse applications. [11][12][13][14][15][16][17][18][19][20] As in thin-film devices, the success of nanodevices similarly relies on the capability of controlling the transport and electrical properties of the selected materials. Doping via introducing electron donor or acceptor elements into the host crystal is a successful approach in thin-film or planar electronic/optoelectronic devices. However, such doping approach remains a challenge for nanostructured materials. To date, while n-and p-type dopings have been achieved in Si, [11][12] InP, [13] CdS, [14] and GaN [15] nanowires/ nanoribbons, many issues of doping, such as control of doping type and conductivity, remain largely untapped or unresolved. For ZnO nanostructures, group III elements (Al, Ga, or In) are commonly used to substitute Zn to induce n-type conductivity. The success of doping is often accompanied and characterized by changes in optical, electrical, and/or structural properties of ZnO nanostructures. For example, Al-doped ZnO nanowires exhibited a blue shift from 3.29 to 3.34 eV in the cathodoluminescent (CL) spectra.[21] Ga 2 O 3 was also employed to dope n-type ZnO nanofibers grown in a vaporphase transport process. [22] however switched to n-type after two months storage in an ambient environment. Despite the considerable efforts, rational synthesis of ZnO nanostructures with tunable n-type conductivity is not available. The as-synthesized ZnO nanostructures are often randomly oriented, and thus have limited applications in optoelectronic devices. Therefore, it is necessary to have a better understanding of the doping efficiency and transport properties of ZnO nanostructures. Herein, we report a controlled growth and doping process of well-aligned ZnO nanowire (NW) arrays via thermal evaporation. The growth direction of ZnO NWs was found to depend on the dopant content, and NW conductivity could be varied over two orders of magnitude. The electrical properties of ZnO NWs were characterized using single-nanowire field-effect transistors (FETs). Figure 1 shows the electron microscopy images of ZnO NW arrays synthesized on a-plane sapphire substrates. The content of Ga 2 O 3 in the source mixtures was varied from 0 to 1 at %. The representative NWs synthesized with 0, 0.2, and 1 at % of Ga 2 O 3 are denoted as samples A, B, and C, respectively. Both the undoped (Fig. 1a and b) and Ga-doped (Fig. 1c) ZnO NWs are aligned vertically on the substrates, and uniform over a large area. The NWs have a uniform dia...

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“…Devices exhibited very good rectification ratio, substantially low leakage current and indicate formation of rectifying behavior between ZnO and n-type SiC with a noticeable superiority for 4HSiC substrates. These values are better than values previously reported, where more sophisticated and expensive techniques were used [6,9]. In Fig.3.b, ln J-V characteristics show doping nature effects on Schottky diodes.…”

Section: Accepted Manuscriptmentioning

confidence: 52%

“…A decade ago, Alivov et al [7,8] reported on the growth of ZnO/p-6HSiC heterostructures diodes by plasma-assisted molecular-beam epitaxy (MBE). In the same time, Yuen et al [9] demonstrated the possibility to fabricate ZnO: Al/p-4HSiC heterojunction light-emitting diodes (LEDs) by a filtered cathodic vacuum arc technique. More recently, Y.T.…”

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confidence: 99%

SiC polytypes and doping nature effects on electrical properties of ZnO-SiC Schottky diodes

Rebaoui

Bouiajra

Abid

et al. 2017

Microelectronic Engineering

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SiC polytypes and doping nature effects on electrical properties of ZnO-SiC Schottky diodes, (2017), doi:10.1016/j.mee.2017 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT AbstractElectrical properties of ZnO/SiC Schottky diodes with two SiC polytypes and N and P doping are investigated. Characterization was performed through I-V and C-V-f measurements. Schottky barrier height (Φ b ), ideality factor (n), and series resistance (R s ) were extracted from forward I-V characteristics.(Φ b ), carrier's concentrations (N d -N a ) and (R s ) frequency dependence were extracted from C-V-f characteristics. The extracted n values suggest that current transport is dominated by interface generationrecombination and/or barrier tunneling mechanisms. When changing SiC polytypes, the rectifying ratio of ZnO/n-4HSiC is found to be twice that of ZnO/n-6HSiC. A change in doping nature gave a leakage current ratio of 40 between ZnO/p-4HSiC and ZnO/n-4HSiC. These results indicate that ZnO/p-4HSiC diodes have a complex current transport compared to diodes on n-type SiC. From I-V measurements, barrier height values are 0.63eV, 0.65eV and 0.71 eV for heterojunction grown on n-6HSiC, n-4HSiC and p-4HSiC, respectively. C-V measurements gave higher values indicating the importance of interface density of states. N ss values at 1MHz frequency are 4.54×10 11 eV -1 cm -2 , 3×10 12 eV -1 cm -2 and 8.13×1010 eV -1 cm -2 for ZnO/n-6HSiC, ZnO/n-4HSiC and ZnO/p-4HSiC, respectively. Results indicate the importance of SiC polytypes and its doping nature.

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Control of conduction type in Al- and N-codoped ZnO thin films

Cited by 85 publications

References 20 publications

Design of shallow acceptors in ZnO through early transition metals codoped with N acceptors

Design of shallow acceptors in ZnO through early transition metals codoped with N acceptors

Tunable n‐Type Conductivity and Transport Properties of Ga‐doped ZnO Nanowire Arrays

SiC polytypes and doping nature effects on electrical properties of ZnO-SiC Schottky diodes

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