scholarly journals Pulsed Laser Ablation Growth and Doping of Epitaxial Compound Semiconductor Films

1995 ◽  
Vol 397 ◽  
Author(s):  
Douglas H. Lowndes ◽  
Christopher M. Rouleau ◽  
D. B. Geohegan ◽  
A. A. Puretzky ◽  
M. A. Strauss ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Compound Semiconductors ◽  
Compound Semiconductor ◽  
Ex Situ ◽  
Semiconductor Films ◽  
Time Resolved ◽  
Control Film ◽  
Ion Probe

ABSTRACTPulsed laser ablation (PLA) has several characteristics that are potentially attractive for the growth and doping of chemically complex compound semiconductors including (1) stoichiometric (congruent) transfer of composition from target to film, (2) the use of reactive gases to control film composition and/or doping via energetic-beam-induced reactions, and (3) low-temperature nonequilibrium phase formation in the laser-generated plasma “plume.” However, the electrical properties of compound semiconductors are far more sensitive to low concentrations of defects than are the oxide metals/ceramics for which PLA has been so successful. Only recently have doped epitaxial compound semiconductor films been grown by PLA. Fundamental studies are being carried out to relate film electrical and microstructural properties to the energy distribution of ablated species, to the temporal evolution of the ablation pulse in ambient gases, and to beam-assisted surface and/or gas-phase reactions. In this paper we describe results of ex situ Hall effect, high-resolution x-ray diffraction, transmission electron microscopy, and Rutherford backscattering measurements that are being used in combination with in situ RHEED and time-resolved ion probe measurements to evaluate PLA for growth of doped epitaxial compound semiconductor films and heterostructures. Examples are presented and results analyzed for doped II–VI, I–III–VI, and column-Ill nitride materials grown recently in this and other laboratories.

scholarly journals Effect of Ambient Gas Pressure on Pulsed Laser Ablation Plume Dynamics and Znte Film Growth

1995 ◽  
Vol 397 ◽  
Author(s):  
CM. Rouleau ◽  
D.H. Lowndes ◽  
M.A. Strauss ◽  
S. Cao ◽  
A.J. Pedraza ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
High Energy ◽  
Gas Pressure ◽  
Ex Situ ◽  
Extended Defect ◽  
Ion Probe ◽  
Ambient Gas ◽  
Probe Measurements

ABSTRACTEpitaxial thin films of nitrogen-doped p-ZnTe were grown on single-crystal, semi-insulating GaAs substrates via pulsed laser ablation of a stoichiometric ZnTe target. Both low pressure nitrogen ambients and high vacuum were used. Results of in situ reflection high energy electron diffraction (RHEED) and time-resolved ion probe measurements have been compared with ex situ Hall effect and transmission electron microscopy (TEM) measurements. A strong correlation was observed between the nature of the film's surface during growth (2-D vs. 3-D, assessed via RHEED) and the ambient gas pressures employed during deposition. The extended defect content (assessed via cross-sectional TEM) in the region >150 nm from the film/substrate interface was found to increase with the ambient gas pressure during deposition, which could not be explained by lattice mismatch alone. At sufficiently high pressures, misoriented, columnar grains developed which were not only consistent with the RHEED observations but also were correlated with a marked decrease in Hall mobility and a slight decrease in hole concentration. Ion probe measurements, which monitored the attenuation and slowing of the ion current arriving at the substrate surface, indicated that for increasing nitrogen pressure the fast (vacuum) velocity-distribution splits into a distinct fast and two collisionally-slowed components or modes. Gas-controlled variations in these components mirrored trends in electrical properties and microstructural measurements.

scholarly journals Time-Resolved Quadrupole Mass Spectrometric Studies on Pulsed Laser Ablation of TiO2

1999 ◽  
Vol 18 (3) ◽  
pp. 99-109 ◽  
Author(s):  
Yongxin Tang ◽  
Zhenhui Han ◽  
Qizong Qin
Keyword(s):  
Laser Ablation ◽  
Continuous Wave ◽  
Center Of Mass ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Ionic Species ◽  
Mass Spectrometric ◽  
Quadrupole Mass ◽  
Time Resolved ◽  
Ambient Oxygen

Pulsed laser ablation of TiO2 at 355 nm and 532 nm has been investigated using an angleand time-resolved quadrupole mass spectrometric technique. The major ablated species include O (m/e = 16), O2 (m/e = 32), Ti (m/e = 48), TiO (m/e = 64) and TiO2 (m/e = 80). The time-of-flight (TOF) spectra of ablated species are measured for the ionic and neutral ablated species, and they can be fitted by a Maxwell – Boltzmann (M – B) distribution with a center-of-mass velocity. The measured angular distributions of the ionic species (O+ and Ti+) and the neutral species (O and Ti) can be fitted with cos⁡nθ and a cos⁡θ + (1−a)cos⁡nθ, respectively. In addition, a continuous wave oxygen molecular beam is introduced into the ablated plume, and the enhancement of the signal intensities of TiO is observed. It implies that the ablated Ti atoms/ions species can react with ambient oxygen molecules in the gas phase. In the meanwhile, the physicochemical mechanism of pulsed laser ablation of TiO2 is discussed.

scholarly journals Cluster Generation Under Pulsed Laser Ablation Of Compound Semiconductors

2010 ◽  
Author(s):  
Alexander V. Bulgakov ◽  
Anton B. Evtushenko ◽  
Yuri G. Shukhov ◽  
Igor Ozerov ◽  
Wladimir Marine ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Compound Semiconductors ◽  
Cluster Generation

Spectrum analysis of plasma produced by pulsed laser ablation of GaAs

2007 ◽  
Vol 73 (2) ◽  
pp. 231-239 ◽  
Author(s):  
AI HUA LIU
Keyword(s):  
Laser Ablation ◽  
Ambient Pressure ◽  
Pulsed Laser ◽  
Emission Spectra ◽  
Diagnostic Technique ◽  
Pulsed Laser Ablation ◽  
Stark Broadening ◽  
Experimental Conditions ◽  
Time Resolved ◽  
Excited Atoms

Abstract.A time-resolved diagnostic technique was used to investigate the emission spectra from the plasmas produced by 1.06 μm, 10 ns pulsed laser ablation of semiconductor GaAs. The characteristics of the species in plasma produced at different ambient pressure were analyzed. The full width at half maximum of the spectral line was measured and analyzed according to obtained spectra of the excited atoms; several line broadening factors were estimated according to our experimental conditions and the results indicate that the Stark broadening is the main broadening mechanism. Under the assumption of local thermodynamic equilibrium, the time evolution of electron number density was deduced from the Stark broadening measurements.

In-situ and ex-situ investigations of pulsed laser ablation of Y target

2011 ◽  
Vol 520 (1) ◽  
pp. 117-120 ◽  
Author(s):  
A. Lorusso ◽  
F. Gontad ◽  
A. Perrone
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Ex Situ

Time Resolved Diagnostic of Dual-Pulsed Laser Ablation on Graphite Targets

2006 ◽  
Author(s):  
R. Sanginés de Castro ◽  
C. Sánchez Aké ◽  
H. Sobral ◽  
M. Villagrán-Muniz
Keyword(s):  
Laser Ablation ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Time Resolved
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