Self-assembling SiGe and SiGeC nanostructures for light emitters and tunneling diodes

Eberl, K.; Schmidt, Oliver G.; Duschl, R.; Kienzle, O.; Ernst, E; Rau, Y. R.

doi:10.1016/s0040-6090(00)00830-0

Cited by 44 publications

(25 citation statements)

References 27 publications

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“…Electron localization with a band offset of U e ‡ 100 meV was also reported in Ref. [9] for undoped Ge/Si nanostructures.…”

Section: Effect Of Sb Dopingsupporting

confidence: 75%

“…The broad QDSL band in the low-energy part of the PL spectrum is attributed to the optical transitions in the Ge/Si columns between holes, localized in the QDs, and electrons, tied to the interface by Coulomb interaction [8,9,[26][27][28][29][30][31][32]. At temperatures T £ 10 K the fine periodic structure of the QDSL band is distinctly observed.…”

Section: Luminescence Properties and Initial Electronic Structurementioning

confidence: 99%

“…The localization of electrons in the Ge/Si interface is mainly determined by the Coulomb interaction, i.e., by the indirect exciton binding energy, which is constant and equals 25 meV [36]. The latter value is close to kT at room temperature, making an observation of the QDSL band at room temperature quite difficult [8][9][10][11][12][13]26]. In our highly strained Sb-doped QDSLs the potential well for electrons is deeper due to the tensile strain-induced lowering of the conduction band.…”

Section: (A)mentioning

confidence: 99%

“…This fact, however, cannot be the reason for the observed red shift of the QDSL PL peak either. Available experimental data on the activation energy for the QD PL band in Ge/Si structures are very controversial and scattered between 15 meV and 183 meV [9,12,26,37]. It is noteworthy that only values between 21 meV and 46 meV are attributed to the electron subsystem in Ref.…”

Section: (A)mentioning

confidence: 99%

“…Although arrays of self-assembled Ge islands grown by the StranskiKrastanow mode on silicon have been studied quite intensively, just a few research teams have reported about PL [8,9] and electroluminescence (EL) data [10][11][12][13]. Probably, due to the low emission intensity, the internal quantum efficiency (QE) measured at room temperature for Ge/Si light emitting diode (LED) at 1.42 lm has been reported only in two studies with the following results: 5 · 10 -4 % [11] and 0.015% [13].…”

Section: Introductionmentioning

confidence: 99%

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Miniband-related 1.4–1.8 μm luminescence of Ge/Si quantum dot superlattices

et al. 2006

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The luminescence properties of highly strained, Sb-doped Ge/Si multi-layer heterostructures with incorporated Ge quantum dots (QDs) are studied. Calculations of the electronic band structure and luminescence measurements prove the existence of an electron miniband within the columns of the QDs. Miniband formation results in a conversion of the indirect to a quasi-direct excitons takes place. The optical transitions between electron states within the miniband and hole states within QDs are responsible for an intense luminescence in the 1.4-1.8 lm range, which is maintained up to room temperature. At 300 K, a light emitting diode based on such Ge/Si QD superlattices demonstrates an external quantum efficiency of 0.04% at a wavelength of 1.55 lm.

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“…Electron localization with a band offset of U e ‡ 100 meV was also reported in Ref. [9] for undoped Ge/Si nanostructures.…”

Section: Effect Of Sb Dopingsupporting

confidence: 75%

Section: Luminescence Properties and Initial Electronic Structurementioning

confidence: 99%

Section: (A)mentioning

confidence: 99%

Section: (A)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Miniband-related 1.4–1.8 μm luminescence of Ge/Si quantum dot superlattices

et al. 2006

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Room Temperature Superlinear Power Dependence of Photoluminescence from Defect-Free Si/Ge Quantum Dot Multilayer Structures

Cirlin

Talalaev

Zakharov

et al. 2002

phys. stat. sol. (b)

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Low-dimensional semiconductor structures, in particular quantum dots (QD) have attracted continuously increased interest from the viewpoints of fundamental physics and of device application. The strained SiGe/Si system, expected to play a dominant role in monolithic integration of Si-based opto-and microelectronics, is still a subject of numerous investigations (see, e.g., [1,2]). Optical properties from Ge islands have been widely studied, e.g., to analyse the complex transition and recombination phenomena in multilayer structures [3]. Recently, few papers reported on the room temperature photoluminescence (PL) originating from Si/Ge QD structures [4-6], however, no detailed investigations on the optical properties were presented. In the present work we would like to report on the fabrication of defect-free multilayer structures containing Ge QD layers in a Si matrix exhibiting strong PL at 1.55 mm at room temperature. This intensity is only ten times lower than that measured at low temperatures. PL integrated intensity versus excitation density shows unambiguously super-linear behavior with m = 1.6.Experimentally, multilayer Si/Ge structures were grown by molecular beam epitaxy (MBE). The structure of the samples consisted of 20 periodic Ge layers (0.7 nm Ge in each layer) separated by 5.5 nm Si spacers. The first 2 nm of each Si spacer were intentionally doped with antimony (Sb). The substrate temperature was kept through the whole growth at 600 C. Structural properties were examined by transmission electron microscope (TEM, JEM 4010). The optical properties were characterised by PL measurements. An argon laser (2.54 eV) was used as excitation source. A cooled Ge photodiode (Edinburgh Instruments) was used as a detector. Figure 1 presents a typical cross-section high-resolution TEM (a) and a plan-view TEM (b) image. Despite the small thickness of the Si spacer used, no structural defects were observed through the structure. The lateral size of the Ge islands amounted to about 80 nm, their heights lay in a range of 3 to 5 nm. The larger heights were found to be in the middle of the structure. Surprisingly abrupt interfaces were formed and no significant intermixing was observed even at the relatively high substrate temperature of 600 C. The average density of Ge QD is about 1 Â 10 10 cm --2 (see, e.g., Fig. 1b). The islands are quite regularly arranged and exhibit well pronounced square-based shape.One goal of the MBE growth was to influence the electronic properties of the grown multilayer structure by, e.g., Sb doping. PL spectra of the samples with different doping levels show that there is a significant effect of the Sb atom concentration on the optical properties. For a relatively small doping level estimated from SIMS data (n % 10 17 cm --3 ) a maximum of PL intensity was achieved. Higher or lower Sb concentrations lead to a decrease of the PL intensity by several times. At the highest doping levels (n % (5-7) Â 10 18 cm --3 ) the maximum of the PL peak shifts towards higher energies. This effect might be...

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Thermal Properties and Heat Transport in Silicon‐Based Nanostructures

Chang

Tsybeskov

2010

Silicon Nanocrystals

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IntroductionFor the past 40 years, crystalline Si (c-Si) continues to be the major material for microelectronics, and modern silicon technology is superior compared to other semiconductors (e.g., II-VI and III-V compounds). In addition to the unique electronic and structural properties of bulk c-Si, silicon dioxide (SiO 2 ) and Si/SiO 2 interfaces, single-crystal Si possesses one of the best known lattice thermal conductivity [1,2]. This exceptional heat conductance is critically important for Si device heat management and circuit reliability. However, most of the modern complementary metal-oxide-semiconductor (CMOS) platforms are no longer single-crystal Si wafers but rather thin layers of Si-on-insulator (SOI), ultrathin strained Si and SiGe heterostructures that are the foundation of SiGe bipolar transistors (HBTs), and high-mobility metal-oxide-semiconductor field-effective transistors (MOSFETs). Major properties of these Si-based nanostructures are very different from those of bulk c-Si. For example, thermal conductivity in ultrathin SOI layers, SiGe alloys, and Si/SiGe nanostructures could be reduced by more than an order of magnitude compared to that in c-Si [3-6], and heat dissipation has become an important issue for modern nanoscale electronic devices and circuits. Thus, the understanding and improvement of heat management in Si-based nanostructures is critically important for the evolution of microelectronic industry.On the other hand, many interesting applications of nanostructured Si (ns-Si) in photonic devices and CMOS-compatible light emitters were recently discussed [7][8][9][10][11]. These ns-Si materials and devices can be produced by electrochemical anodization (i.e., porous Si [12]), chemical vapor deposition (CVD) using thermal decomposition of SiH 4 [13-15], Si ion implantation into a SiO 2 matrix [16], and deposition of amorphous Si/SiO 2 layers followed by thermal crystallization [17][18][19]. These ns-Si materials and devices produce an efficient and tunable light emission in the near-infrared and visible spectral region [20,21]. Also, it has been shown that under photoexcitation with energy density >10 mJ/cm 2 , optical gain is possibly Silicon Nanocrystals: Fundamentals, Synthesis and Applications. Edited by Lorenzo Pavesi and Rasit Turan

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Self-assembling SiGe and SiGeC nanostructures for light emitters and tunneling diodes

Cited by 44 publications

References 27 publications

Miniband-related 1.4–1.8 μm luminescence of Ge/Si quantum dot superlattices

Miniband-related 1.4–1.8 μm luminescence of Ge/Si quantum dot superlattices

Room Temperature Superlinear Power Dependence of Photoluminescence from Defect-Free Si/Ge Quantum Dot Multilayer Structures

Thermal Properties and Heat Transport in Silicon‐Based Nanostructures

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