Spontaneous formation of Ge nanocrystals with the capping layer of Si3N4 by N2+ implantation and rapid thermal annealing

Jung, Min-Cherl; Lee, Young Mi; Shin, Hyun‐Joon; Kwon, Deok‐Hwang; Kim, Miyoung; Ko, Changhun; Han, Mei; Park, Yongsup

doi:10.1016/j.tsf.2010.06.045

Cited by 3 publications

(2 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…p-type Ge (111) single crystal surface (Nilaco Corporation) was initially cleaned by Ne + ion (high purity 99.999%) sputtering for 3 hours with a beam energy of 1 kV under a chamber base pressure of 1.0 × 10 −6 Torr. The sputtering method was applied until the O 1 s and C 1 s core-level peaks, at 650 eV, of the incident photon energy measured by HRXPS had disappeared 5 . The N 2 + implantation was done in N 2 gas (high purity 99.999%) for 1 hour with ion beam energy of 2 kV using the same pressure.…”

Section: Methodsmentioning

confidence: 99%

“…Ge is an indirect gap semiconductor, with two main electronic transitions, the first at 0.67 eV (indirect) the second at 0.8 eV (direct) and Ge nanocrystals ( nc -Ge) are one of the candidates for such applications due to their superior charge storage performance 1 2 3 . Several methods can be used to form nc -Ge such as Ge ion implantation 4 , N 2 + implantation 5 , SiGe oxidation 6 , thermal annealing of Ge thin films 7 8 , molecular beam epitaxy 9 , and co-deposition of Ge with SiO 2 3 10 11 . Ge nanocrystals have been shown to emit photoluminescence (PL) covering a vast spectrum in both the visible, with wavelengths ranging from 460 nm to 515 nm and in the infrared at around 1600 nm 4 10 11 12 13 14 15 16 17 .…”

mentioning

confidence: 99%

See 1 more Smart Citation

Carrier trapping and confinement in Ge nanocrystals surrounded by Ge3N4

Park

Chan

Reid

et al. 2016

Sci Rep

Self Cite

View full text Add to dashboard Cite

We investigated the optical properties of Ge nanocrystals surrounded by Ge 3 N 4 . The broad emission ranging from infrared to blue is due to the dependence on the crystal size and preparation methods. Here, we report high resolution Photoluminescence (PL) attributed to emission from individual Ge nanocrystals (nc-Ge) spatially resolved using micro-photoluminescence and detailed using temperature and power-dependent photoluminescence studies. The measured peaks are shown to behave with excitonic characteristics and we argue that the spread of the nc-Ge peaks in the PL spectrum is due to different confinement energies arising from the variation in size of the nanocrystals.Semiconductor nanostructures are arguably the most promising technology for future optoelectronics and memory device applications due to the recent rapid advances in nanoscale science and technqiues [1][2][3] . Ge is an indirect gap semiconductor, with two main electronic transitions, the first at 0.67 eV (indirect) the second at 0.8 eV (direct) and Ge nanocrystals (nc-Ge) are one of the candidates for such applications due to their superior charge storage performance [1][2][3] . Several methods can be used to form nc-Ge such as Ge ion implantation 4 , N 2 + implantation 5 , SiGe oxidation 6 , thermal annealing of Ge thin films 7,8 , molecular beam epitaxy 9, and co-deposition of Ge with SiO 2 3,10,11 . Ge nanocrystals have been shown to emit photoluminescence (PL) covering a vast spectrum in both the visible, with wavelengths ranging from 460 nm to 515 nm and in the infrared at around 1600 nm 4,10-17 . PL previously reported for nc-Ge has been shown to give broad emission spectra in the visible range with a full width at half maximum (FWHM) of a few hundred meV. This broad spectrum indicates an ensemble effect of the nanocrystals 4,10-15 , individual nc-Ge emission has never been resolved. The origin of visible PL from nc-Ge has been discussed by Kanemitsu et al. who reported a change in the Ge crystalline structure at diameters below 4 nm, departing from the usual diamond structure. This new structure, beyond the 4 nm limit, is thought to allow for their observed visible luminescence with the character of a direct transition 11 . Contrary to Kanemitsu, Giri et al. reported observation of PL from Ge nanocrystals of a larger diameter, 4~13 nm embedded in SiO 2 4 . In addition, S. Takeoka et al. measured PL that was dependent on Ge nanocrystals with average diameters of 0.9~5.3 nm embedded in SiO 2 . The PL was found to range from the near infrared at a diameter of 5.3 nm to an energy slightly larger than the band gap of bulk Ge as the nanocrystal size decreased down to 0.9 nm 17 . The broadness of the emission can be atributed to the dependence of the PL energy on nanocrystal size, but the precise explanation of the origin of this emission remains unclear. Ensemble effects have obscured the finer details of the PL spectrum, contributing to the controversy as to the origin of the Ge nanocrystal luminescence.In this paper, Ge nanocrystals with a d...

show abstract

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Carrier trapping and confinement in Ge nanocrystals surrounded by Ge3N4

Park

Chan

Reid

et al. 2016

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

The trapping of N2 molecules and the reduction in its bonding length in Ge(001) due to N2+ ion implantation

Lee

Yun

Hong

et al. 2011

Journal of Applied Physics

View full text Add to dashboard Cite

To find the cause of N2 → N + N dissociation in Ge(001) at low temperature, the N2+ ion implantation process was carried out on a Ge(001) substrate, followed by rapid thermal annealing (RTA). After N2+ ion implantation, the presence of N2 molecules and the chemical states of GeNx were determined using near-edge x-ray absorption of fine structure (NEXAFS) and high-resolution x-ray photoelectron spectroscopy with synchrotron radiation, respectively. Rapid thermal annealing was performed at 600 °C, after which a change in chemical state from the chemically meta-stable state of GeNx to the stable state of Ge3N4 was observed. In addition, the intensity of the N2 vibration mode peak in NEXAFS was decreased, although it did not completely disappear. To explain the N2 →N + N dissociation at the low temperature, a first-principle calculation for N2 bonding length was performed in both vacuum and Ge(001) states. We confirmed that implantation resulted in the trapping of N2 molecules in Ge(001), and their bonding length was changed from 1.117 to 1.205 Å at a difference energy of 2.529 eV. It was assumed that the relaxed change in the N2 bonding length originated from the dissociation of N2 molecules at low temperature.

show abstract

Chemical states and photoluminescence of Si0.3Ge0.7-nitride film formed by N2+ gas

Lee

Jang

Han

et al. 2011

Applied Physics Letters

View full text Add to dashboard Cite

We investigated chemical states and photoluminescence of Si0.3Ge0.7-nitride film with a surface that was modified by N2+ ion implantation and rapid thermal annealing (RTA). By increasing the implantation time, the chemical bonding between Si and Ge was directly broken, and subnitrides were formed. We also observed the N2 vibration mode peak in the x-ray absorption spectra, but after RTA, this peak disappeared completely. SiNx was transformed to the stable Si3N4. However, GeNx with various chemical states, including Ge3N4 and nanocrystalline Ge, were formed. Photoluminescence observations at room temperature showed strong visible luminescence at wavelengths of 460 and 515 nm.

show abstract

Spontaneous formation of Ge nanocrystals with the capping layer of Si3N4 by N2+ implantation and rapid thermal annealing

Cited by 3 publications

References 12 publications

Carrier trapping and confinement in Ge nanocrystals surrounded by Ge3N4

Carrier trapping and confinement in Ge nanocrystals surrounded by Ge3N4

The trapping of N2 molecules and the reduction in its bonding length in Ge(001) due to N2+ ion implantation

Chemical states and photoluminescence of Si0.3Ge0.7-nitride film formed by N2+ gas

Contact Info

Product

Resources

About