Emission and absorption spectroscopic studies of a reactor used to grow germanium thin films by photodissociating GeH4 at 248 nm with an excimer laser are described here. For every Ge or GeH (A→X) transition examined, the dependence of the emission line intensity on pump laser fluence was found to be quadratic, indicating that Ge and GeH have a common precursor which is itself produced by the simultaneous absorption of two 5-eV photons. This conclusion is supported by the known photochemistry of SiH4 and CH4 in the ultraviolet and the laser wavelength and intensity thresholds for the growth of Ge films. The short (∼2 μs) lifetime of GeH2 in the reactor suggests that the immediate precursor to Ge and GeH is the germyl radical, GeH3. The activation energy for Ge film growth in the temperature range 300≤T≤500 K has been measured to be 2.0±0.5 kcal/mole which suggests that the limiting mechanisms for the film growth rate are a gas-phase reaction and surface desorption of residual gases rather than surface diffusion. Radiation trapping on several Ge emission lines and absorption measurements at 422.6 nm indicate that the steady-state Ge number density in the reactor is ∼1012 cm−3 which is sufficient to account for the observed film growth rates. Spatial profiles of the atomic Ge and GeH emission from the reactor have been measured with a resolution of ∼100 μm.

Spectra attributed to transitions from the 5sσ a 3Σu+ metastable state of Kr2 to excited Rydberg states have been observed by intracavity and multipass absorption and by laser excitation spectroscopy. Four distinct Rydberg series converging on the X 2Σu+ core of Kr2+ have been identified. Rotational structure is not resolved in any of the observed spectra. Most of the spectra can be assigned to vibronic transitions in the nfλ(3Πg,3Σg+) and npλ(3Πg,3Σg+)←a 3Σu+ series by analogy with similar spectra in the lighter rare gas dimers. The 6pπ 3Πg←a 3Σu+ and 8pσ 3Σg+←a 3Σu+ transitions observed in the ∼19 200–18 200 cm−1 region exhibit many bands with v′≠0 in their (v′–v″) vibrational band system developments. The higher n value members of these and other observed series are dominated by (0–0) transitions. All series are perturbed in a few energy regions by states built on the excited ion core states A 2Π3/2g and B 2Π3/2u. Laser excitation spectra for the 8pσ 3Σg+←a transition obtained by monitoring various 5p→5s emission lines of atomic krypton suggest that the 8pσ 3Σg+ Rydberg state of Kr2 is predissociated by a repulsive potential correlated with Kr 5p[3/2]1+Kr(1S0). The lowest ionization limit of Kr2 (relative to a 3Σu+,v=0) was determined to be 28 484±5 cm−1.

The ultraviolet emission spectrum of GeH has been examined following the two photon-initiated dissociation of germane (GeH4) at 248 nm. The most prominent peaks lying between ∼250 and 340 nm are tentatively assigned to B 2Σ(v′=0)→X 2Π1/2,3/2 (v′) transitions. From this premise, the vibrational constants for the X 2Π states have been estimated to be ωe=(1949±5) cm−1, ωexe=16.5±2.0 cm−1, and ωeye=(0.7±0.3) cm−1. Also, the radiative lifetime of the lowest vibrational levels of the GeH A 2Δ state in transitions to ground has been measured to be 12±2 ns.

Lowtemperature highly preferred polycrystalline Si film growth on crystallized amorphous Si by reactive ion beam deposition J. Vac. Sci. Technol. B 7, 1338 (1989; 10.1116/1.584535Lowtemperature formation of polycrystalline silicon films on silicon oxide by pyrolyzing silane in a tungsten heater Polycrystalline Si and Ge films have been grown on amorphous Si0 2 substrates (average Tsubstrate < 120°C) by the photodissociation ofSiH 4 /N 2 or GeH4/He mixtures, respectively, using pulsed ArF (193 nm) and KrF (248 nm) excimer lasers. For both Si and Ge, the film growth rate exhibited a strong dependence on laser wavelength and beam intensity I, where 15<1..;;.20 MW cm-2 • Asdeposited films exhibited average grain sizes of up to 0.5 f.,lm and the grains were equiaxed with a random orientation. Ge films doped with _10 20 cm-3 Al were obtained by the simultaneous photodissociation of AI(CH 3 b and GeH 4 .

Experiments are described in which semiconductor or metal films are grown from the vapor phase by photodissociating or photoionizing diatomic or polyatomic molecules.The photolysis of GeH4 at 248 nm (iiw = 5 eV) is initiated by a two photon process that liberates the germylene radical GeH2.Spatially and temporally-resolved concentration profiles for several excited states of GeH and atomic Ge have been measured near the substrate.Thin indium films have been deposited on nickel substrates by dissociatively ionizing indium monoiodide (InI) to produce In+ -I-ion pairs.The dynamics of ion pair production for thallium iodide or InI vapor photoexcited at 193 nm have been studied by combining an excimer laser with microwave absorption techniques.