Enhanced Free Exciton and Direct Band-Edge Emissions at Room Temperature in Ultrathin ZnO Films Grown on Si Nanopillars by Atomic Layer Deposition

被引：26

作者：

Chang, Yuan-Ming ^{[1
]}

Shieh, Jiann ^{[3
]}

Chu, Pei-Yuan ^{[1
]}

Lee, Hsin-Yi ^{[2
,4
]}

Lin, Chih-Ming ^{[5
]}

Juang, Jenh-Yih ^{[1
]}

机构：

[1] Natl Chiao Tung Univ, Dept Electrophys, Hsinchu 300, Taiwan

[2] Natl Chiao Tung Univ, Dept Mat Sci & Engn, Hsinchu 300, Taiwan

[3] Natl United Univ, Dept Mat Sci & Engn, Miaoli 360, Taiwan

[4] Natl Synchrotron Radiat Res Ctr, Hsinchu 300, Taiwan

[5] Natl Hsinchu Univ Educ, Dept Appl Sci, Hsinchu 300, Taiwan

来源：

ACS APPLIED MATERIALS & INTERFACES | 2011年 / 3卷 / 11期

关键词：

ultrathin; ZnO; Si nanopillars; atomic layer deposition; free exciton; OPTICAL-PROPERTIES; QUANTUM DOTS; ZINC-OXIDE; ULTRAVIOLET; PHOTOLUMINESCENCE;

D O I：

10.1021/am201062t

中图分类号：

TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

Room-temperature ultraviolet (UV) luminescence was investigated for the atomic layer deposited ZnO films grown on silicon nanopillars (Si-NPs) fabricated by self-masking dry etching in hydrogen-containing plasma. For films deposited at 200 degrees C, an intensive UV emission corresponding to free-exciton recombination (similar to 3.31 eV) was observed with a nearly complete suppression of the defect-associated broad visible range emission peak. On the other hand, for ZnO films grown at 25 degrees C, albeit the appearance of the defect-associated visible emission, the UV emission peak was observed to shift by similar to 60 meV to near the direct band edge (3.37 eV) recombination emission. The high-resolution transmission electron microscopy (HRTEM) showed that the ZnO films obtained at 25 degrees C were consisting of ZnO nanocrystals with a mean radius of 2 nm embedded in a largely amorphous matrix. Because the Bohr radius of free-exictons in bulk ZnO is similar to 2.3 nm, the size confinement effect may have occurred and resulted in the observed direct band edge electron-hole recombination. Additionally, the results also demonstrate order of magnitude enhancement in emission efficiency for the ZnO/Si-NP structure, as compared to that of ZnO directly deposited on Si substrate under the same conditions.

引用

页码：4415 / 4419

页数：5

共 35 条

[1] Enhancement of conductivity and transmittance of ZnO films by post hydrogen plasma treatment [J].

Cai, P. F. ;

You, J. B. ;

Zhang, X. W. ;

Dong, J. J. ;

Yang, X. L. ;

Yin, Z. G. ;

Chen, N. F. .

JOURNAL OF APPLIED PHYSICS, 2009, 105 (08)

[2] Enhanced visible photoluminescence from ultrathin ZnO films grown on Si-nanowires by atomic layer deposition [J].

Chang, Yuan-Ming ;

Jian, Sheng-Rui ;

Lee, Hsin-Yi ;

Lin, Chih-Ming ;

Juang, Jenh-Yih .

NANOTECHNOLOGY, 2010, 21 (38)

[3] Optical properties of ZnO nanostructures [J].

Djurisic, Aleksandra B. ;

Leung, Yu Hang .

SMALL, 2006, 2 (8-9) :944-961

[4] Photoluminescence investigation of the carrier recombination processes in ZnO quantum dots and nanocrystals [J].

Fonoberov, VA ;

Alim, KA ;

Balandin, AA ;

Xiu, FX ;

Liu, JL .

PHYSICAL REVIEW B, 2006, 73 (16)

[5] Radiative lifetime of excitons in ZnO nanocrystals: The dead-layer effect [J].

Fonoberov, VA ;

Balandin, AA .

PHYSICAL REVIEW B, 2004, 70 (19) :1-5

[6] Polar optical phonons in wurtzite spheroidal quantum dots: theory and application to ZnO and ZnO/MgZnO nanostructures [J].

Fonoberov, VA ;

Balandin, AA .

JOURNAL OF PHYSICS-CONDENSED MATTER, 2005, 17 (07) :1085-1097

[7] Origin of ultraviolet photoluminescence in ZnO quantum dots: Confined excitons versus surface-bound impurity exciton complexes [J].

Fonoberov, VA ;

Balandin, AA .

APPLIED PHYSICS LETTERS, 2004, 85 (24) :5971-5973

[8] ZnO quantum dots: Physical properties and optoelectronic applications [J].

Fonoberov, Vladimir A. ;

Balandin, Alexander A. .

JOURNAL OF NANOELECTRONICS AND OPTOELECTRONICS, 2006, 1 (01) :19-38

[9] Origin of defect-related green emission from ZnO nanoparticles: effect of surface modification [J].

Gong, Yinyan ;

Andelman, Tamar ;

Neumark, Gertrude F. ;

O'Brien, Stephen ;

Kuskovsky, Igor L. .

NANOSCALE RESEARCH LETTERS, 2007, 2 (06) :297-302

[10] Room-temperature photoluminescence from ZnO/ZnMgO multiple quantum wells grown on Si(111) substrates [J].

Gu, X. Q. ;

Zhu, L. P. ;

Ye, Z. Z. ;

He, H. P. ;

Zhang, Y. Z. ;

Huang, F. ;

Qiu, M. X. ;

Zeng, Y. J. ;

Liu, F. ;

Jaeger, W. .

APPLIED PHYSICS LETTERS, 2007, 91 (02)

← 1 2 3 4 →