The transition to single crystal of ion‐implanted amorphous Si and Ge layers is described in terms of a liquid‐phase epitaxy occurring during pulsing‐laser irradiation. A standard heat equations including laser light absorption was solved numerically to give the time evolution of temperature and melting as a function of the pulse energy density and its duration. The structure dependence of the absorption coefficient and the temperature dependence of the thermal conductivity were accounted for in the calculations. In this model the transition to single crystal occurs above a well‐defined threshold energy density at which the liquid layer wets the underlying single‐crystal substrate. Experiments were performed in ion‐implanted amorphous layers of thicknesses ranging between 500 and 9000 A. The energy densities of the Q‐switched ruby laser ranged between 0.2 and 3.5 J/cm2; time durations of 20 and 50 ns were used. The experimental data are in good agreement with the calculated values for the amorphous thickness–energy−density threshold. The model deals mainly with plausibility arguments and does not account for processes occuring in the near‐threshold region or below the melting temperature.

A melting model for pulsing‐laser annealing of implanted semiconductors

Ion implantation for isolation of III-V semiconductors

The phenomenology is reviewed for several enhanced diffusion mechanisms: the normal ionization-enhanced diffusion mechanism, the Bourgoin mechanism, the energy-release mechanism and some recoil mechanisms. Application of these mechanisms are discussed for crystalline and amorphous semiconductors, super-ionic materials and insulators in radiation damage, impurity and self-diffusion, ion-implantation, and dislocation-motion-experiments.

Enhanced diffusion mechanisms

Ion-induced defects in semiconductors

Decades of experimental and theoretical studies have brought some useful insights about what defines resistance to amorphization by radiation damage; however, the problem is still viewed as generally unsolved. I review ideas and concepts that have been put forward to help with understanding this problem. I then discuss how the type of interatomic force is relevant for resistance to amorphization, with covalency of bonding stabilizing the damage and making material amorphizable. On a more detailed level, I suggest that resistance to amorphization of a complex non-metallic material is defined by the competition between the short-range covalent and long-range ionic forces. I follow this with a review of experimental data on 116 materials, to illustrate that the type of interatomic force can generally explain the resistance to amorphization. I conclude by discussing how the proposed picture is related to models proposed previously, and by suggesting some possible future research.

http://iopscience.iop.org/article/10.1088/0953-8984/16/49/R03/pdf

Understanding resistance to amorphization by radiation damage

The present paper gives a survey about the defect generation caused by ion implantation of GaAs, InAs, GaP, and InP. By combining Rutherford backscattering spectrometry, optical spectroscopy, and transmission electron microscopic methods, further information concerning the kinetics of the defect production as well as the type of defects created is obtained. Generally, the defect concentration in the region of implantation parameters investigated can be described by the energy density deposited into nuclear processes. Below critical values of the nuclear deposited energy density in GaAs weakly damaged layers containing point defects and point defect clusters are produced. With increasing nuclear deposited energy density an increasing number of amorphous zones is created due to manifold overlap of the initial defect clusters. The results indicate that in GaAs and InAs already at relatively low implantation temperatures, the amorphization occurs via homogeneous defect nucleation. The results obtained for GaP...

Defect production during ion implantation of various AIIIBV semiconductors

High energy ion beam analysis of solids

Investigation of laser induced diffusion and annealing processes of arsenic-implanted silicon crystals

Radiation damage and refractive index of ion-implanted LiNbO3

Under definite implantation conditions (small ion masses, sufficiently small ion fluences, and high implantation temperature) in III–V compounds weakly damaged layers are produced, which exhibit characteristic properties near the optical edge and an only slight increase of dechanneling of backscattered light ions. Especially for GaAs, InP, and GaP an exponential dependence of the near edge absorption coefficient on the photon energy according to K ∼ exp (ħω/E1) with E1 = 0.52 eV for GaAs, 0.33 eV for InP, and 0.6 eV for GaP is observed. From theoretical considerations it is concluded that this behaviour is connected with the existence of high concentrations of complexes containing antisite defects and vacancies. Combining optical measurements with TEM and measurements of the temperature dependence of the dechanneling gives further information about the structure of weakly damaged GaAs layers. The results of a complex analysis of weakly damaged GaAs and other III–V compound layers and first ideas about the damage structure in such layers are discussed.



In III–V-Verbindungshalbleitern entstehen unter bestimmten Implantationsbedingungen (niedrige Ionenmassen, hinreichend niedrige Ionendosis und hohe Implantationstemperatur) schwach geschadigte Schichten, die charakteristische optische Eigenschaften im Bereich der Bandkante aufweisen und zu einer nur geringen Erhohung der Dekanalisierung ruckgestreuter leichter Ionen fuhren. Insbesondere findet man in GaAs, InP und GaP im Bereich der Bandkante eine exponentielle Anhangigkeit des Absorptionskoeffizienten von der Photonenenergie entsprechend K ∼ ∼ exp (ħω/E1) mit E1 = 0,52 eV fur GaAs, 0,33 eV fur InP und 0,6 eV fur GaP. Aus theoretischen Untersuchungen kann gefolgert werden, das dieses Verhalten mit der Existenz einer hohen Konzentration von Defektkomplexen verbunden ist, die Antisite-Defekte und Vakanzen enthalten. Erganzende Untersuchungen mittels TEM und zur Temperaturabhangigkeit der Dekanalisierung liefern weitere Informationen uber die Struktur der schwach geschadigten GaAs-Schichten. Es werden die Ergebnisse einer komplexen Analyse schwach geschadigter GaAs- und anderer III—V-Halbleiterschichten und erste Vorstellungen uber die Struktur der Defekte in diesen Schichten diskutiert.

Gerhard Götz

Papers

Defect production during ion implantation of various AIIIBV semiconductors

High energy ion beam analysis of solids

Investigation of laser induced diffusion and annealing processes of arsenic-implanted silicon crystals

Radiation damage and refractive index of ion-implanted LiNbO3

Defects in Weakly Damaged Ion‐Implanted GaAs and Other III–V Semiconductors