Optical Diagnostics for Thin Film Processing

Herman, Irving P.

doi:10.1146/annurev.physchem.54.011002.103824

Cited by 29 publications

(24 citation statements)

References 280 publications

(244 reference statements)

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“…A significant downshifted PL peak when going from the thinnest (1.5 nm) MQW sample via the 3 nm to the 4.5 nm MQW is a clear evidence of the influence of the internal electric field on the emission peak energy of the QWs. For the 1.5 nm and 4.5 nm wide QW samples, respectively, a doublet peak is observed at low temperatures, which is consistent with the case when the interfaces exhibit growth islands of lateral dimensions much larger than the exciton Bohr radius [15].…”

Section: Resultssupporting

confidence: 82%

Exciton localization behaviour in different well width undoped GaN/Al0.07Ga0.93N nanostructures

Sabooni

Esmaeili

Haratizadeh³

et al. 2007

Opto-Electronics Review

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We report results from optical spectroscopy such as photoluminescence (PL) and time resolved photo-luminescence (TRPL) techniques from different well width MOCVD grown GaN/Al0.07Ga0.93N MQW samples. There is evidence of localization at low temperature in all samples. The decay time of all samples becomes non-exponential when the detection energy is increased with respect to the peak of the emission. Localization of carriers (excitons) is demonstrated by the “S-shape” dependences of the PL peak energies on the temperature. The time-resolved PL spectra of the 3-nm well multi quantum wells reveal that the spectral peak position shifts toward lower energies as the decay time increases and becomes red-shifted at longer decay times. There is a gradient in the PL decay time across the emission peak profile, so that the PL process at low temperatures is a free electron-localized hole transition.

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Section: Resultssupporting

confidence: 82%

Exciton localization behaviour in different well width undoped GaN/Al0.07Ga0.93N nanostructures

Sabooni

Esmaeili

Haratizadeh³

et al. 2007

Opto-Electronics Review

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“…For a 50/50 mixture of SF 6 and Ar at 40 W, the measured temperature varies with total pressure as shown in Fig. 3.…”

Section: A Variation With Pressurementioning

confidence: 99%

“…[3][4][5][6] Emission of the active species is compared to that of an inert gas ͑He, Ar, Kr, or Xe͒ that serves as an actinometer. At low pressure and low power, where neutral species collision frequencies are relatively small, the emission intensity of the noble gas species will track changes in the electron energy distribution function ͑EEDF͒, electron density, and neutral gas density.…”

Section: Introductionmentioning

confidence: 99%

Emission, thermocouple, and electrical measurements in SF6/Ar/O2 SiC etching discharges

Brown

Scofield

Ganguly

2003

Journal of Applied Physics

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In SiC etching plasma devices, we have recorded plasma emission from Ar, F, and O atoms in SF6/Ar/O2 rf discharges as a function of pressure, input power, and mixture fraction. At fixed power, the emission intensities rise nearly linearly with increasing pressure between 100 and 300 mTorr; with pressure increases to 600 mTorr, the emission intensity rolls off due to the increase in collisional de-excitation. At fixed pressure, Ar and O atom emission shows a similar functional dependence on input power with a roll off at the higher powers due to decreasing reduced electric field strength (E/n, where n denotes the number density). In contrast, the F atom emission increase with increasing power is nearly linear. This reflects the fact that F atoms are produced by dissociative attachment of SF6 (for lower E/n conditions) in addition to direct electron impact dissociation. Electrical measurements, with a variable interelectrode gap discharge, indicate that the electric field to pressure (E/p) ratio does drop with increasing input power. Thermocouple measurements show that the ground electrode temperature increases with increasing power. The dissociative attachment of SF6 increases with increasing temperature as well. The SiC etch rate increases nearly linearly with input power up until the polymer buildup becomes the rate limiting process. At fixed pressure, the Ar emission from the 750 nm line decreases with increasing additions (up to 10%) of O2. This is due to resonantly enhanced quenching of the 4p (13.5 eV) manifold by oxygen atoms. In marked contrast, the F atom emission intensity increases suggesting F atom production by neutral species chemistry. Over the pressure (100–600 mTorr) and power (20–60 W) range studied, the Ar 750 nm emission line serves as a good actinometer for the 704 nm F line provided that there is not a high degree (or changing degree) of O2 dissociation. Resonant deactivation of the 750 nm line through collisional interaction with O atoms, can make the 750 nm line problematic. Under such conditions our previous work indicates that the Ar 641 nm line can provide an alternative actinometer. The excited state of the 641 nm transition lies above the O atom ionization limit making it immune from resonant quenching.

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“…This monitoring technique is now very common in epitaxial growth, but is also widely adopted for endpoint detection in plasma etch systems [37]. The monitoring wavelength in this study was 670 nm, and the beam was focussed onto the sample at normal incidence through a window in the ceiling of the process chamber.…”

Section: Dry-etching For Pattern Transfermentioning

confidence: 99%

Nanofabrication of gallium nitride photonic crystal light-emitting diodes

Khokhar

Parsons

Hubbard

et al. 2010

Microelectronic Engineering

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a b s t r a c tWe describe a comparison of nanofabrication technologies for the fabrication of 2D photonic crystal structures on GaN/InGaN blue LEDs. Such devices exhibit enhanced brightness and the possibility of controlling the angular emission profile of emitted light. This paper describes three nano lithography techniques for patterning photonic crystal structures on the emitting faces of LEDs: direct-write electron beam lithography, hard stamp nanoimprint lithography and soft-stamp nanoimprint lithography with disposable embossing masters. In each case we describe variations on the technique as well as its advantages and disadvantages. Complete process details have been given for all three techniques. In addition, we show how high performance GaN dry etch techniques, coupled with optical process monitoring can transfer resist patterns into underlying GaN material with high fidelity.

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Optical Diagnostics for Thin Film Processing

Cited by 29 publications

References 280 publications

Exciton localization behaviour in different well width undoped GaN/Al0.07Ga0.93N nanostructures

Exciton localization behaviour in different well width undoped GaN/Al0.07Ga0.93N nanostructures

Emission, thermocouple, and electrical measurements in SF6/Ar/O2 SiC etching discharges

Nanofabrication of gallium nitride photonic crystal light-emitting diodes

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