M. Gauneau

Growth of double doped semi-insulating indium phosphide single crystals

Semi-insulating (SI) InP, co-doped with a shallow acceptor (Hg or Cd) and a deep donor (Ti or Cr) has been grown by the gradient freeze method or by the liquid encapsulated Czochralski (LEC) technique. Three dopant couples have been studied: Hg+Ti, Hg+Cr and Cd+Cr. The crystals have been characterized by spark source mass spectrometry (SSMS), secondary ion mass spectrometry (SIMS) and thermally dependent Hall (TDH) effect using the Van der Pauw technique. Deduced from the activation energy measurements, the donor deep levels of titanium and chromium have been found to be at Ec-0.53 eV and Ev+0.56 eV, respectively. SIMS profiles on SI substrates annealed at 975°C show that SI InP (Ti, Hg) is more thermally stable than SI InP(Fe) and SI InP(Cr, Hg or Cd).

Silicon implantation in semi-insulating bulk InP; Electrical and photoluminescence measurements

Abstract Hall effect measurements and low temperature photoluminescence properties of silicon implanted with doses between 1×10 13 and 5×10 14 cm -2 , and capless annealed (at 750 °C for 15 min) semi-insulating InP: Fe samples are presented. A monotonic decrease in the measured electrical activity is observed with increasing Si + implanted dose. From photoluminescence analysis (77 and 6.5 K) the above result is tentatively interpreted by a dose-dependent increase of the concentration of shallow (Zn) and deep (Mn) acceptors in the implanted region. This is confirmed by SIMS measurements which reveal, for the first time, that the residual Zn atoms exhibit a tendency to getter towards the surface due to high dose implants.

Aspects of the selective deposition of TiSi2 by LRP-CVD for use in ULSI submicron technology

Abstract TiSi2 layers are deposited in a short time cycle using a rapid thermal processing system at reduced pressure and temperature, called LRP for limited reaction processing. The use of TiCl4 from a liquid or from a solid source gives selective layers with minimal or no substrate consumption. However, two main problems are studied in this paper which have a strong effect on a technological process: substrate doping behavior under silicide growth and post-annealing reactions and silicide grain size. We present some recent results on the latter as well as recall our interpretation of the TiSi2 formation from a kinetic point of view. Some technological results on 4 inch wafers will also be presented.

Secondary ion mass spectrometry generates swelling of GaSb: Depth resolution and secondary ion yields

The III‐V compound gallium antimonide (GaSb), which has a relatively narrow band gap, is of increasing importance for the fabrication of optoelectronic devices. However, GaSb was shown to swell during high energy ion implantation. The surface upheaval increased with the dose, energy, and mass of implanted ions, reaching heights of about 1 μm under the most harmful conditions. With the low energies used for secondary ion mass spectrometry (SIMS), i.e., between 1 and 20 keV, a similar behavior was observed under cesium bombardment, with elevations of 100 nm, giving rise to abnormal secondary ion yields and depth profile distortions. Here, the phenomenon has been investigated under cesium and oxygen bombardment, between 1.25 and 14.5 keV, with doses from 1015 cm−2 to above 1017 cm−2. The swelling of the material is confirmed whatever the nature of primary ions. The mechanism is related to the damage caused by the primary ion bombardment rather than to the presence of oxygen. The critical damage threshold of ...

Oxygen enhancement induced by ionic implantation in scandium diphthalocyanine thin films

Secondary ion mass spectrometry correlated with ionic implantations has allowed us to determine oxygen bulk concentration in scandium diphthalocyanine thin films. This concentration, around 2×1020 atom cm−3, increases by a factor 20–25 in implanted areas. This oxygen enhancement is observed for oxygen implantation but as well for xenon, caesium, or iodine implantation, and therefore is not dependent on the nature of the implanted atoms. The oxygen concentration saturates in the damaged region but its quantity depends on the energy loss and on the fluence; the larger the damaged layer, the larger the region where the enhancment takes place. The phenomenon will be tentatively related to the creation of free radicals induced by bond breaking occurring during the implantation process.But, other explanations including more severe degradations of the molecular material cannot be dismissed.

Inhomogeneity in a semi-insulating indium phosphide ingot

Abstract A whole semi-insulating iron-doped indium phosphide ingot, grown by the conventional Czochralski growth method, is investigated by cartographical methods. Experiments are made on samples cut along the 〈001〉 growth axis: inhomogeneities are clearly evidenced by scanning photoluminescence measurements at 300 K. The decreasing in the PL intensity is found to follow the iron concentration increase. The scattering laser tomography technique is also applied to this ingot. The number of the defects thus revealed is found to decrease from the head to the tail of the ingot. On the opposite, the size of the defects increases towards the tail.

Spatial investigation of an iron-doped indium phosphide ingot

Abstract A whole Czochralski-grown iron-doped indium phosphide ingot was investigated by various techniques, all along the growth axis. Scanning photoluminescence, secondary ion mass spectroscopy and sheet resistance techniques were used. The average photoluminescence intensity and the iron concentration were found to be correlated. Samples of the ingot were annealed and implanted. For low ion-implantation doses, the electrical properties were mainly dependent on the initial properties of the ingot.

Growth of low-dislocation semi-insulating InP(Fe, Ga)

Abstract Isoelectronic doping of InP single crystals is effective in reducing the dislocation density. We have grown large (5 cm diameter) LEC InP doped with Ga, As and GaAs. The impurity content was determined by spark source mass spectrometry (SSMS) analysis. The effective segregation coefficients k Ga and k As were found to be respectively 4 and 1. Up to the studied content (10 20 cm -3 ) arsenic is ineffective in reducing dislocation density. Inversely InP(Ga) is low dislocated for [Ga]=10 19 cm -3 in the melt. But due to the k Ga value, Ga concentration in the crystal decreases from the top to the bottom and only the first part of the pulled crystal has a low dislocation density. By double doping with Ga and Fe we have grown a semi-insulating crystal which is dislocation free on a large zone (diameter ≈ 20 mm) in the central part of the cone. Electrical and optical characteristics of InGaAs epilayers grown on InP(Ga, Fe) are not affected by Ga presence in the substrate. Moreover, in the case of Be doped InGaAs epilayers, SIMS profiles show that there is no Be diffusion in the InP(Fe, Ga) substrate contrary to the InP(Fe) substrate.

Ion implantation damage and annealing in GaSb

Abstract The production and annealing of damage in GaSb implanted at room temperature with 150 keV Ar+-ions over a wide dose range are investigated by Rutherford backscattering spectrometry in combination with the channeling technique and by transmission electron microscopy. Above a critical dose close to 4 × 1013 cm−2, the introduction of radiation damage induces a swelling of the implanted region. This phenomenon is observed to be related to the formation of a layer containing voids and microtwins, and, at higher doses, porous polycrystalline GaSb. For doses below the swelling threshold, the rapid thermal annealing process produces a good recovery of defects. Otherwise, for doses higher than the critical dose, the annealing process is less efficient. When the swelling is low, there is regrowth of the porous layer after annealing at 600°C but large voids remain, and, when the swelling is high, the regrowth procedure is unsuccessful.

X-ray topography and tem studies of (Ga,Fe)-double-doped LEC grown InP crystals

Abstract In order to improve the structural quality of semi-insulating Fe-doped LEC InP crystals, a few percent of Ga, which is an isovalent impurity was added to the melt. The assessment of the obtained double-doped InP crystals was made by X-ray diffraction, transmission electron microscopy and secondary ion mass spectrometry, before and after annealing at high temperature. The defect distribution and density as well as the thermal stability will be discussed with regard to those obtained when Ga or Fe is used alone.