scholarly journals Preparation and Optical Properties of Ge and C-Induced Ge Quantum Dots on Si

1999 ◽  
Vol 571 ◽  
Author(s):  
K. Eberl ◽  
O. G. Schmidt ◽  
O. Kienzle ◽  
F. Ernst

ABSTRACTPure Ge epitaxially grown on Si (100) at high temperatures forms typically 100 nm lateral size islands on top of a 3–4 monolayer thick wetting layer. In stacked layers of Ge dots pronounced vertical alignment is observed if the thickness of the Si spacer layers is smaller than about 50 nm. Pregrowth of a small amount of C on Si substrate induces very small 10 nm size Ge quantum dots after deposition of about 2 to 3 monolayers Ge. Photoluminescence (PL) studies indicate a spatially indirect radiative recombination mechanism with the no-phonon line strongly dominating. Strong confinement shift in the 1–2 nm high and 1Onm lateral size dots results in low activation energies of 30 meV, which causes luminescence quenching above 50K.For large stacked Ge islands with 13 nm thin Si spacer layers we observe a significantly enhanced Ge dot-related PL signal up to room temperature at 1.55μm wave length. This is attributed to a spatially indirect transition between heavy holes confined within the compressively strained Ge dots and two-fold degenerated A state electrons in the tensile strained Si between the Ge stacked dots.

1999 ◽  
Vol 570 ◽  
Author(s):  
K. Eberl ◽  
O. G. Schmidt ◽  
O. Kienzle ◽  
F. Ernst

ABSTRACTPure Ge epitaxially grown on Si (100) at high temperatures forms typically 100 nm lateral size islands on top of a 3–4 monolayer thick wetting layer. In stacked layers of Ge dots pronounced vertical alignment is observed if the thickness of the Si spacer layers is smaller than about 50 nm. Pregrowth of a small amount of C on Si substrate induces very small 10 nm size Ge quantum dots after deposition of about 2 to 3 monolayers Ge. Photoluminescence (PL) studies indicate a spatially indirect radiative recombination mechanism with the no-phonon line strongly dominating. Strong confinement shift in the 1–2 nm high and 1Onm lateral size dots results in low activation energies of 30 meV, which causes luminescence quenching above 50K.For large stacked Ge islands with 13 nm thin Si spacer layers we observe a significantly enhanced Ge dot-related PL signal up to room temperature at 1.55μm wave length. This is attributed to a spatially indirect transition between heavy holes confined within the compressively strained Ge dots and two-fold degenerated Δ state electrons in the tensile strained Si between the Ge stacked dots.


2004 ◽  
Vol 224 (1-4) ◽  
pp. 165-169 ◽  
Author(s):  
Z Pei ◽  
P.S Chen ◽  
S.W Lee ◽  
L.S Lai ◽  
S.C Lu ◽  
...  

2020 ◽  
Vol 67 (12) ◽  
pp. 1120-1127
Author(s):  
Hongqiang Li ◽  
Jianing Wang ◽  
Jinjun Bai ◽  
Shanshan Zhang ◽  
Sai Zhang ◽  
...  

1998 ◽  
Vol 533 ◽  
Author(s):  
O. G. Schmidt ◽  
K. Eberl ◽  
S. Schieker ◽  
N. Y. Jin-Phillipp ◽  
F. Phillipp ◽  
...  

AbstractFifty layers of carbon-induced germanium dots, separated by 9.6 nm Si, are stacked by solid source molecular beam epitaxy. Each dot layer consists of 0.2 monolayers of pre-deposited carbon and 2.4 monolayers of post-grown Ge. These carbon-induced germanium dots are only 10 to 15 nm in diameter and 1 to 2 nm in height. Vertical alignment due to penetrating strain fields of underlying dot layers is not observed. Unlike to an identical structure without the pre-growth of carbon, a variety of advantageous aspects such as strain compensation, strongly enhanced no-phonon photoluminescence at a wavelength of around 1.3 μm and the possibility of effective waveguiding make this stack of C-induced Ge islands an attractive structure for Si based optoelectronic devices.


2000 ◽  
Vol 638 ◽  
Author(s):  
A. Beyer ◽  
E. Müller ◽  
H. Sigg ◽  
S. Stutz ◽  
C. David ◽  
...  

AbstractGermanium quantum dots embedded in silicon have been used in the past to improve the opto-electronic properties of Si based materials. The idea is to overcome the limitation of the indirect band gap of Si by a strong localization of the carriers in quantum dots. However, the Ge quantum dots provide a strong carrier confinement only for the holes, the electrons are only weakly confined in the Si. In this study we embedded the Ge quantum dots in strained Si quantum wells grown on relaxed SiGe buffer layers. The strained Si quantum wells provide a confinement of the electrons in the vicinity of the Ge dots.The structures were deposited on planar as well as on patterned substrates by molecular beam epitaxy. The structural and optical properties of the samples were analyzed using high resolution cross sectional transmission electron microscopy (TEM) as well as low temperature photoluminescence. The size of the mesa structures have been used as experimental parameter. Relaxed buffer layers grown on line shaped mesa structures show a strongly reduced dislocation density. Consequently the deep luminescence attributed to dislocations in the buffer layers is strongly reduced and pronounced photoluminescence of the quantum structures grown on top of the buffer layers can be observed.


2009 ◽  
Vol 1 (2) ◽  
pp. 82-86 ◽  
Author(s):  
Rajkumar Singha ◽  
Samaresh Das ◽  
Achintya Dhar ◽  
Samir K. Lahiri ◽  
Samit K. Ray ◽  
...  

2012 ◽  
Vol 5 (5) ◽  
pp. 052101 ◽  
Author(s):  
Toshiki Tsuboi ◽  
Xuejun Xu ◽  
Jinsong Xia ◽  
Noritaka Usami ◽  
Takuya Maruizumi ◽  
...  

1999 ◽  
Vol 571 ◽  
Author(s):  
J. L. Liu ◽  
W. G. Wu ◽  
G. Jin ◽  
Y. H. Luo ◽  
S. G. Thomas ◽  
...  

ABSTRACTInter-sub-level transitions in p-type modulation-doped Ge quantum dots are observed. The structure is grown by molecular beam epitaxy and consists of 30 periods of Ge quantum dots separated by 6 nm boron-doped Si layers. An absorption peak in the mid-infrared range is observed at room temperature by Fourier transform infrared spectroscopy, and is attributed to the transition between the first two heavy hole states of the Ge quantum dots. This study suggests the possible use of modulation-doped Ge quantum dots for improved infrared detector application.


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