J. C. Bourgoin

Identification of EL2 in GaAs

Combining electron paramagnetic resonance under optical excitation, deep level transient spectroscopy, electron irradiation, annealing, and quenching on LEC semi‐insulating GaAs and lightly Si‐doped material grown in the same way as the semi‐insulating material, we have shown that (i) the irradiated material contains two types of defects related to the antisite AsGa, one As∇Ga, present before irradiation, identified to EL2 from its characteristic photoquenching behavior and the other As*Ga, created by the irradiation, stable under photoexcitation; (ii) As∇Ga anneals partially under a 850u2009°C thermal treatment followed by a quench and the remaining defects are transformed into As*Ga; (iii) further annealing around 120u2009°C converts As*Ga into As∇Ga, the process being thermally activated (0.5±0.2 eV). From these results and using observations of absorption on vibrational modes of the C‐As interstitial pair in electron irradiated material, we are able to conclude that As*Ga is the isolated antisite and As∇Ga, i...

Transient capacitance spectroscopy in heavily compensated semiconductors

Abstract We have developed the theory of the capacitance transient of a junction in the case where the usual approximation, namely that the defect concentration N T is not negligible compared to the free carrier concentration, is not fulfilled. We show that the correct analysis of this transient by the so-called Deep Level Transient Spectroscopy technique must take into account the fact that, during the transient, the width of the space charge region varies. The validity of the expressions obtained for the shift of the signature (variation of the emission rate vs temperature) and for the concentration N t is verified by comparison with experimental results obtained for electron induced defects in n -GaAs.

Defects in organometallic vapor‐phase epitaxy‐grown GaInP layers

Nonintentionally doped metalorganic vapor‐phase epitaxy Ga1−x InxP layers, having an alloy composition (x = 0.49) corresponding to a lattice matched to GaAs, grown by metalorganic chemical vapor deposition, have been studied by capacitance‐voltage and deep‐ level transient spectroscopy techniques. They are found to exhibit a free‐carrier concentration at room temperature of the order of 1015 cm−3. Two electron traps have been detected. The first one, at 75 meV below the conduction band, is in small concentration (∼ 1013 cm−3) while the other, at about 0.9 eV and emitting electrons above room temperature, has a concentration in the range 1014–1015 cm−3.

Formation of AsGa antisite defects in electron‐irradiated GaAs

The anion antisite AsGa formation in electron‐irradiated GaAs of various compositions and dopings has been studied by electron paramagnetic resonance. The results are interpreted in a new model based on carrier recombination enhanced mobile arsenic interstitials exchanging sites with gallium‐substituted impurities.

Luminescence of the DX center in AlGaAs

Low‐temperature photoluminescence of the D X center in the near band edge and in the near‐infrared region is interpreted within the small lattice relaxation model. The 1.5 μm luminescence band is attributed to an internal transition between the excited D X state and its ground‐state level.

The behavior of As precipitates in low-temperature-grown GaAs

We analyze the kinetics associated with the concentration and the growth of As precipitates during annealing in low-temperature-grown GaAs layers. We correlate them with that associated with the annealing of the As antisite related defect. This allows us to deduce that all these kinetics are governed by the mobility of the As interstitial whose migration energy is 0.44 eV.

Defects in low‐temperature electron‐irradiated p‐type silicon

Defects in monocrystalline silicon have been studied in the past, in particular, defects induced by room‐temperature electron and proton irradiations on both n‐ and p‐type materials, and most of the corresponding defects have been tentatively identified. However, there are still several questions which remain to be answered such as the nature and behavior of the defects introduced in the range 4–300 K. In this work Czochralski‐grown p‐type material has been irradiated at three different temperatures (90, 200, and 300 K) and characterized by deep‐level transient spectroscopy (DLTS) and lifetime measurements. The data show that the defects created after irradiations at 90 and 200 K are different from those reported in the literature for irradiations at 4, 77, and 300 K, showing that three annealing steps exist between 4 and 300 K. These defects are characterized and a tentative identification of them is made. Finally, an attempt to detect the defects responsible for the lifetime, i.e., the recombination cen...

Detection of the metastable state of the EL2 defect in GaAs

Using a classical photocapacitance technique, we have transformed the well-known EL2 defects, related to the As antisite in GaAs, into their metastable states. Using the capacitance, we have monitored the temperature dependence of the electron occupancy of these metastable states at thermal equilibrium. From this study, we deduce that a level located at 40 meV below the conduction band is associated with electron ionization from the metastable EL2 states.

Structural and Defect Study of Low Temperature INP Grown by Gas Source Molecular Beam Epitaxy

The low temperature growth procedure used in the case of GaAs to introduce high concentrations of deep traps such as arsenic antisite defects has been extended to the growth of InP by gas source molecular beam epitaxy. The low temperature growth of InP induces a strong group V stoechiometric deviation (of the order of +1%). On the other hand, Secondary Ion Mass Spectrometry reveals high levels of hydrogen ranging from 3.10 18 to 3.10 19 cm −3 depending on growth temperature. Undoped layers are found to be resistive without any post annealing. Annealing experiments above 250°C lead to conductive layers suggesting a passivation effect of both shallow donors and acceptors by hydrogen.

Antisite incorporation during epitaxial growth of GaAs

We have modelled the incorporation of As antisite defects in GaAs during epitaxial growth. The model assumes that the antisite is introduced as a result of the incorporation of an As2 molecule occupying a Ga site without being dissociated. The antisite incorporation is thermally activated with an activation energy of 1.4 eV and a frequency factor of 1012 s−1, resulting in the nondissociation of As2 molecules on the surface. The results of the modelling are compared with experimental data obtained by molecular beam epitaxy at low temperature and by vapor phase techniques at high temperature. The concentration of antisites has been determined versus the growth rate and the substrate temperature using electrical methods, infrared absorption and through the change of the lattice mismatch. The temperature and the growth rate dependences of Arsenic antisite obtained from our model are in agreement with the experimental results, the fitting parameters being independent of the growth conditions.