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Numerical investigations have been performed for modeling the global temperature field of an industrial liquid phase epitaxy (LPE) facility and to estimate the temperature fluctuations in a Te-rich solution during the LPE growth. The numerical results agreed well with experimental data and therefore provide reliable reference points for experimenters for further improvements of the growth conditions. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Ge 1− x Si x ( x ⩽10 at%) single crystals were grown with the float zone technique using a monoellipsoid mirror furnace. The feed rod consisted of pre-synthesized Ge 0.95 Si 0.05 polycrystalline material with an initial composition of pure germanium. Several boron-doped (1–2×10 17 at cm −3 ) crystals were grown using 〈1 0 0〉 Ge seeds. Taking advantage of the pre-synthesized feed rods, a defined macrosegregation could be achieved in the grown crystals with a linear slope at the beginning (≈0.5 at% mm −1 ) followed by a plateau region with a constant silicon distribution (Si concentration up to 10 at%, fluctuation rate: ⩽±0.3 at%). The etch pit density was in the range of 7×10 3 –2×10 4 cm −2 . Micrographs of the etched crystals show sharp changes in interface curvature at the crystal edges. These distortions of the interface morphology are a direct function of the Si concentration; they are considered to be caused by solutal Marangoni convection. Theoretical considerations show that the flow direction and strength vary significantly from a solutal Marangoni convection regime directly in front of the solid–liquid interface to a thermal Marangoni convection regime within the bulk melt.

GeSi single crystals in the range Si⩽10 at% have been grown on Ge 〈1 1 1〉-seed crystals by the vertical Bridgman method in a radiation heated mirror furnace. The diameter of the crystals was 9 mm, their length about 30–40 mm. Axial and radial macrosegregation have been measured by energy dispersive analysis by X-ray (EDAX), microsegregation was investigated using interference contrast microscopy. The average EPD is in the range 6×10 4 –1×10 5 cm −2 and is enhanced at the seed/crystal interface and in the part grown in the vicinity of the container wall. Measurements with a Bartels five crystal diffractometer of the 〈1 1 1〉 peak resulted in FWHM (full-width at half-maximum) values of 20 to 40 arcsec, compared to the theoretical value of 17 arcsec. The FWHM values of the bound excitons, determined by photoluminescence, are in the range 2.5–4.5 meV, which are the best values reported hitherto, and show a linear enlargement with increasing silicon concentration. The segregation coefficients of Ga, In, P, As, and Sb fit well to a linear interpolation between the Ge and Si values.

Undoped and chlorine-doped CdTe single crystals of 2.4 cm diameter were grown from the vapour phase by a modified Markov method. Boundary conditions for the control of partial pressures were realized applying a heat sink at different temperatures. The influence of the sink on dopant incorporation was investigated by photoluminescence. Transitions of free and bound excitons dominate the PL spectra in cases of undoped CdTe. The characteristic luminescence of the A-centre was identified in CdTe : Cl. Alpha measurements yielded a product of carrier mobility and lifetime of 2 × 10−4 cm2/V.

V and Ga doped CdTe single crystals with one inch diameter were grown without wall contact in a semi-closed vapour phase system (modified Markov method). By vapour transport modelling, we demonstrate that volatile impurities and excess species are enabled to condense in a heat sink connected to the growth chamber. Vapour composition and component fluxes are controlled by the temperature profile, in particular by the sink temperature. The grown crystals exhibit pronounced {{1 1 1}}, {{1 1 0}} and {{1 0 0}} facetting. The influence of the deep heat sink on interface stability is discussed in terms of growth morphology and formation of inclusions. Piezobirefringence measurements indicate nearly stress-free growth. The resistivities of the grown crystals are up to 3 × 10 9 Ω · cm .

Vanadium and gallium doped CdTe crystals were grown from the vapour phase (modified Markov method) and (Cd 0.9 Zn 0.1 )Te:V from the melt (vertical Bridgman). The crystals were characterized by photoinduced current transient spectroscopy (PICTS), photoluminescence (PL) and time dependent charge measurements (TDCM). Transitions from different charge states (V 2+ /V 3+ ) of the vanadium donor have been observed in the V-doped crystals by PICTS. A shallow donor level (dE = 0.068 eV) and the Ga A-center have been identified by PICTS and PL measurements in CdTe:Ga. In case of V-doping high resistivity is achieved all over the crystal while Ga-doping results in a high resistivity region only in the middle of the crystal. Calculation of the resistivity by means of a compensation model shows that for both dopants an additional not observed deep donor has to be assumed in order to describe the resistivity distributions.

CdTe 0.9 Se 0.1 :Cl is a detector grade material for gamma and X-rays. Its high resistivity and the high mobility lifetime product yield a high charge collection efficiency of 90 percent. CdTe 0.9 Se 0.1 :Cl was used for the first time to built up a strip detector. The detector performance was investigated by a 57 Co source. The signal behaviour, charge collection efficiency and coupling effects were analyzed for different strips. The comparison between the signal amplitude of all strips showed a good homogeneous response for the device. For a single strip a charge collection efficiency of more than 40 percent was obtained.

Te-doped and undoped GaAs single crystals of 6–7 mm diameter and up to 20 mm length have been grown by the floating-zone method. In addition, a Te-doped GaAs single crystal of 20 mm diameter and 20 mm length was successfully grown during the 2nd German Spacelab mission D2. It could be shown that growth rates up to 240 mm/h are possible without losing single crystallinity. Dopant striations due to Marangoni convection have been found, as well as a reduction of the etch pit density compared with that of the starting material.

CdTe:Cl crystals were grown from the liquid and from the vapour phase under microgravity (μg) conditions on board the unmanned EURECA I mission. The resistivity distribution of the grown crystals was measured by time dependent charge measurement (TDCM). Photo induced current transient spectroscopy (PICTS) was used to investigate the deep level properties. The axial resistivity distributions of the crystals grown in space differ significantly from 1 g reference crystals. In the case of vapour growth, these differences can be explained by an additional laminar flow under 1 g conditions. Supercooling has to be considered in growth from a Te zone under μg.

GaSb bulk single crystals with low acceptor concentration were grown from a bismuth solution by the traveling heater method. The result is isoelectronic doping by Bi which gives a variation of the opto-electronic properties as a function of grown length as well as a pronounced microscopic segregation. Photoluminescence spectra at 4K show a decrease of the natural acceptor during growth, which is confirmed by Hall measurements. The electrical properties of this isoelectronic doped GaSb are hole concentrations and mobilities of NA − ND = 1.7 × 1016 cm−3 and μ = 870 cm2Vs at room temperature and NA­ND = 1 × 1016 cm−3 and μ = 4900 cm2/Vs at 77K, respectively. The lowest p-type carrier concentration measured at 300K is NA − ND = 3.3 × 1015 cm−3

Vanadium doped CdTe is studied by electron paramagnetic resonance (EPR), photo-EPR, and optical absorption. The EPR measurements identify vanadium substitutional for Cd in the oxidation states V 2+ and V 3+ . Whereas V 3+ shows the well-known isotropic EPR spectrum, the V 2+ spectrum features triclinic symmetry due to a strong Jahn-Teller coupling. By photo-EPR, the V 2+ /V 3+ -donor level was determined at 0.67 eV below the conduction band. In absorption, additionally to internal crystal field transitions of vanadium, we also observe the recharging process V 3+ to V 2+ .

Low temperature (5 K) spectra of liquid phase electroepitaxially grown sulphur-doped GaSb have been examined. Native acceptor-related transition appears at 777 meV in undoped GaSb and it is shifted by 4–6 meV to lower energy in sulphur-doped layers. The dominant sulphur-related transition S 1 lies at 731–733 meV in different samples. The intensity of this transition is higher than the intensity of the native acceptor-related transition and their ratio increases with the amount of Sb 2 S 3 in the growth melt. Both photoluminescence and photoreflectance measurements have shown that the energy band gap of these sulphur-doped samples ( E G = 732 meV at 295 K) is a little higher in comparison with other published values.

Long-term crystal growth experiments were successfully performed under microgravity conditions during the first flight of the unmanned EURECA-1 mission in the automatic mirror furnace (AMF). Two crystals of sulphur-doped InP with [001] and [111] orientation respectively were grown from indium solution by the travelling heater method (THM). The absence of time dependent buoyancy-driven convection is documented by the lack of type I striations in the space-grown crystals. The sulphur concentration is measured by spatially resolved photoluminescence. As expected, the macrosegregation can be described by a pure diffusion-controlled model which is in good agreement with the findings from the first German spacelab mission D1. Compared to the earth-grown reference samples, both of the space-grown InP crystals show strong disturbances such as inclusions and type II striations. The morphological instabilities are similar to growth disturbances already known from the space-grown MD-ELI-01 from the D1 mission.

Long-term crystal growth experiments were successfully performed under microgravity conditions during the first flight of the unmanned mission EURECA-1 in the automatic mirror furnace (AMF). Two crystals of Al x Ga 1-x Sb with [001] and [111] orientation respectively were grown from gallium solution by the travelling heater method. The grown length of the single crystals is 4.0 mm and 4.2 mm respectively. The space-grown samples show a high microscopic homogeneity which indicates the absence of time dependent convection. From pulse markers a constant growth rate of 0.6 ± 0.1 μm/min is measured which is lower than 0.8 ± 0.1 μm/min obtained in earth grown reference samples. Details about the experiment performance and the growth results are given.

Crystals of the semiconductor Cu0.85In1.05Se2 were grown from the melt. The crystals were characterized by scanning electron microscopy as well as transmission electron microscopy. A coexistence of two phases was found in the entire boules which was detected by energy dispersive spectroscopy and by electron diffraction. High resolution electron microscopy showed a direct intergrowth of both phases.

We investigated the optical properties of defects in CdTe and ${\mathrm{Cd}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Zn}}_{\mathit{x}}$Te (0x1). Residual impurities give rise to specific far infrared absorptions, while metal vacancy-donor complexes (A centers), identified by optically detected magnetic resonance, are characterized by their near infrared (1.4 eV) photoluminescence (PL) properties. The specific zero-phonon-line positions and phonon couplings are worked out for these complexes involving different group-VII (F, Cl, Br, In) or group-III (In, Al) donors. In addition to the A center PL two emission bands are found at 1.135 and at 1.145 eV. The temperature dependences of the PL show that the 1.145 eV luminescence follows the temperature dependence of the band gap, while the energy position of the 1.135 eV band emission shifts to higher energies with increasing temperature. The A-center PL and the luminescence bands at 1.1 eV are investigated throughout the complete alloy composition range form x=0 to 1. The A center and the 1.135 eV band were found to follow the band-gap shift from CdTe to ZnTe, whereas the 1.145 eV luminescence keeps its emission energy constant.

Semi-insulting CdTe bulk crystals were grown from the vapour phase in both closed and semi-open arrangements. The results of the growth experiments are discussed in terms of various electrical and optical characterization methods. Van der Pauw measurements and time dependent charge measurements (TDCM) were used to determine the resistivity. Deep level defects were investigated by means of photoinduced current transient spectroscopy (PICTS). For one of the most important fields of application, detector spectra of the vapour phase material are measured and discussed.

The transition metal ions titanium and vanadium in CdTe are studied by optical absorption, electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD) and optically detected magnetic resonance (ODMR) spectroscopy. Titanium is observed in two different charge states. Ti2+ (3d2) and Ti3+ (3d1) by EPR. Absorption measurements however show only the 3A2 → 3T1(3P) and 3A2 → 1E(1D) internal transitions of Ti2+. This assignment is confirmed by MCD and ODMR measurements. For vanadium-doped CdTe only the V3+ charge state is observed in EPR. In absorption two pronounced absorption bands are seen which are attributed to internal transitions of V3+.

CdTe: Cl crystals were grown from the vapour phase by the sublimation travelling heater method (STHM) in space on board of the unmanned EURECA I mission. They were characterized by time dependent charge measurement (TDCM) and photoinduced current transient spectroscopy (PICTS). Axial cuts of the space grown crystals investigated by TDCM reveal an axial symmetric resistivity distribution along the growth direction, which can be explained by segregation effects of chlorine.

The vapour growth of CdTe:V and CdTe:Ti by the sublimation travelling heater method (STHM) is reported for the first time. Characterization of the crystals has been performed by time dependent charge measurement (TDCM) and photoinduced current transient spectroscopy (PICTS). Axial cuts of CdTe:V crystals showed a very homogeneous and high resistivity distribution in the range of 1010 ω · cm. The PICTS spectra depict three levels which can be attributed to transition metal doping. The expected deep donor level can be identified clearly to be at Ev + 0.95 and 0.94 eV in CdTe:V and CdTe:Ti, respectively.

Several CdTe crystals doped with vanadium (V) or titanium (Ti) were grown by a vertical Bridgman technique and the Sublimation Travelling Heater Method (STHM). Spatially resolved resistivity measurements were performed using the Time Dependent Charge Measurement (TDCM) method. It is shown that V doping leads to a more homogeneous resistivity distribution in contrast to Ti. Photoinduced Current Transient Spectroscopy (PICTS) has been used to characterize the deep levels. Up to three additional levels are introduced through the doping with transition metals.

Semi-insulating titanium and vanadium doped cadmium telluride crystals were grown from the vapour phase. We show results of the electrical characterisation obtained by Hall measurements, photoinduced current transient spectroscopy (PICTS), admittance spectroscopy and time-of-flight measurements. The crystals with a resistivity of about 10 9 Ω · cm showed a deep level, which was identified for CdTe:V at −0.77 eV and a similar value at −0.66 eV for CdTe:Ti, both with reference to the conduction band. The μτ products are almost the same for both materials in the range of 10 −5 cm 2 /V. A compensation model, which was developed for semi-insulating GaAs, is adapted to semi-insulating vanadium- and titanium-doped cadmium telluride. We show that the data from the compensation model correspond to the measured properties.

Both undoped and halogen-doped CdTe bulk crystals were grown in a monoellipsoid mirror furnace using a vapor zone transport method in closed ampoules (sublimation traveling heater method, STHM). Partial pressure gradients in the vapor affect the growth front stability and thus the maximum pulling rate significantly. A thermodynamic consideration leading to a “critical” growth rate J crit for sublimation growth of undoped CdTe in closed systems as well as a comparison with experimental results for halogen-doped material are introduced. In addition to chlorine, bromine and iodine were used as dopants for the first time in CdTe sublimation material. Resistivity measurements and photoluminescence investigations were performed. Resistivities in the range of 1.2 × 10 6 to 8 × 10 8 ω cm were found; the photoluminescence (PL) spectra of doped materials show a band within the defect region that may be assigned to a complex (V 2- Cd ; halogen + Te ) - , the A-center previously found for Cl doping.

The growth of sulphur-doped GaSb by liquid phase electroepitaxy (LPEE) is presented. Antimony sulphide as a sulphur source was used. The epitaxial layers grown at 550°C were compensated p-type. By lowering the growth temperature to 535°C, a higher incorporation of the sulphur into the epitaxial layer was achieved and n-type layers with carrier concentration n = 1 x 1016 cm-3 and Hall mobility μ = 1944 cm2 /V ⊙ot s were grown. The growth rate decreasing by an increase of the amount of antimony sulphide in the melt is reported.

A Te-doped GaAs (100) single crystal of 20 mm diameter and 20 mm length was successfully grown by the floating-zone method during the 2nd German Spacelab mission D2. Dopant striations due to Marangoni convection as well as a reduction of the etch pit density compared to te starting material have been found. The last part of the crystal, grown with the quite high translation rate of 120 mm/h, showed no sign of unstable growth and exhibited properties similar to the parts grown with 3 and 6 mm/h.

The growth of bulk PbI 2 crystals of up to 7 cm 3 volume from highly purified source material is described. The growth method applied is a modified Piper-Polich technique. The phase transitions involved in the growth process are liquid through gaseous to solid.

In Al x Ga 1−x Sb crystals grown by the travelling heater method (THM), spatially resolved photoluminescence and cathodoluminescence measurements were carried out at 77 and 20 K, respectively, to detect the AlSb distribution at convective type I and kinetic type II striations (resolution about 4 μm in diameter). The AlSb microscopic segregation effects in the riser area of type II striations can be explained with the non-steady-state step exchange model.

Bulk Al x Ga 1−x Sb single crystals with various AlSb solid compositions were grown by the travelling heater method (THM) on GaSb substrates. The crystals were grown with a Ga-rich as well as on an Sb-rich solution zone (undoped or doped with Te). We report in this investigation on results obtained by electrical characterization (DLTS, Hall effect) and optical spectroscopy (photoluminescence). Deep centres (DX centre) and shallow centres ( ⌈ and X conduction band derived donors) were investigated.

Using spark-source mass spectrometry, atomic absorption spectrometry and various optical techniques, a study is made of the concentrations of impurities (total and point-defect concentrations), charge carriers and precipitates as well as of their axial distributions in Bridgman crystals grown with and without an extra Cd source. It is found that the concentrations of substitutional impurities are controlled by Cd and Te vacancies which form during the growth process. When the crystals are cooled after growth, part of the Cd vacancies are occupied by impurity atoms, while part of them cluster to form Te precipitates. The vacancy concentrations are modified, and the latter reaction is suppressed, in the case of growth under Cd overpressure. Intentional doping with halogens leads to formation of persistent Te-site donor/Cd-vacancy complexes.

Optically detected and conventional spin resonance investigations have been successful in determining the structure of cation vacancy-donor pairs (A-centers) and anion vacancies ( V Te ) in CdTe. Investigations in the ternary alloy systems Cd1−xZnxTe for the complete range of x show that the A-center binding energy is almost independent of the composition. In CdTe the VTe+/0 level position is 0.2 eV above the valence band and correlation to a deep luminescence band at 1.15 eV can be drawn. In the alloys this photoluminescence band closely follows the conduction band from CdTe to ZnTe. Studies of the spectroscopic g- values of the shallow donors in Cd 1−x Zn x Te show that they shift linearly from -1.69 in CdTe to -0.4 in ZnTe.

During the German Spacelab mission D1 various Crystal Growth Experiments have been successfully performed. The aim of this article is to review those growth studies which have been carried out in ellipsoidal mirror furnace systems. A Floating Zone Technique has been applied to Si whereas GaSb, InP, CdTe and (Pb, Sn) Te have been grown in quartz ampoules by the Travelling Heater Method (THM). One CdTe-growth run used a vapour zone instead of a metallic solution zone. As a main result of all experiments it could be demonstrated that semiconductor crystals may be grown under reduced gravity conditions in a nearly diffusive growth regime.

Single crystals of AlxGa1−xSb with a diameter of 15 mm, a length of more than 10 mm and an Al solid composition ranging from 0.06 to 0.1 have been successfully grown with the travelling heater method (THM). Crystals were grown in quartz ampoules in the monoellipsoidal mirror furnace (AMF) with a ring focus. By using the lamp pulsing technique (LPT), microscopic growth rates as a function of grown length could be measured. The growth of ternary compounds has been analysed theoretically. Combined with growth results, we estimated the material transport coefficients of Al and Sb in the Ga solution.

Aluminium nitride (AIN) layers were grown on sapphire (0 0 01) and on Si-terminated SiC (0 0 01) in a RF-plasma enhanced MBE system with integrated UHV-STM/AFM. The layers have been investigated by cathodoluminescence (CL) and Raman measurements. The CL measurements show defect related transitions in the region of 2-5 eV and resolved excitonic features in the near band-edge region followed by multiple A 1 (LO) replica. From both CL and Raman studies a superior quality of the AIN/SiC layers in comparison to the A1N/sapphire lavers is deduced.

Sulphur-doped InP and tellurium-doped GaSb have been grown by the travelling-heater method from indium and gallium solutions under microgravity and earth conditions. To analyse the growth kinetics on a microscale, time markers were generated during the crystal growth. This is done by rotating the samples and by pulsing the lamp of the mirror-heater. In space grown crystals as well as in the earth grown reference samples, type II striations as traces of macrosteps occured at the beginning and the end of THM growth. It can be shown, that there is a critical growth velocity for macrostep formation. The onset of macrosteps is also influenced by the properties of the seed crystal.

The single crystalline growth of the GaNxSb1-x system is difficult due to the miscibility gap expected for nearly the whole composition range under thermodynamic equilibrium conditions. The gap is determined by the differences of the atomic radii and of the electro negativities for N and Sb. To overcome this problem crystal growth has to be performed under non-equilibrium conditions with kinetically controlled growth, as it is observed for molecular beam epitaxy (MBE) growth. A single crystalline MBE-growth within the miscibility gap has been demonstrated already in the GaAsxN1-x system exhibiting a similar large miscibility gap. GaN:Sb-layers were grown on Si(111)-substrates by MBE using NH3 as a N-source and solid element sources for Ga and Sb. The parameter window for growth was limited due to side reactions like the decomposition of NH3, the desorption of (at high temperature volatile) compounds like Sb and GaSb or the reaction of Sb with NH3. The composition of the layers was analyzed by XRD and RBS. Antimony bulk concentrations of up to 1.6 % could be obtained in GaN. Optical characterization of the samples was performed by CL-measurements and indicate Sb-induced transitions in the 2.2 eV and 1.42 eV range.

The optical properties of the red modification of mercuric iodide (HgJ2) were studied by optical absorption, magnetic circular dichroism, photoluminescence and optically detected magnetic resonance investigations. The experiments demonstrate the involvment of acceptors with energy levels at Ev + 0.14 ± 0.01 eV and 0.15 ± 0.01 eV in the absorption and recombination at 2.2 eV. The g - values are 0.85 and 0.74, respectively.

Crystals of undoped AlSb were grown from Sb-rich solutions at temperatures below 1250 K using the Bridgman method. Carbon crucibles inserted in sealed silica ampoules filled with argon at low pressure gave the best results. High resistivity (ϱ ⋍ 200– 600 Ω cm) polycrystalline material without any voids could be synthesized. Crystals grown at low temperature were particularly resistant to corrosion. Schottky barriers with reverse currents of less than 0.5 μA/mm 2 at 1 V could be prepared in undoped p-type AlSb.

We have studied the growth conditions for bulk In1−xGaxP by using the travelling heater method (THM). Stable growth conditions with respect to the phase diagram of the In-Ga-P system could be achieved for x ⩾ 0.8 and a growth temperature of 900°C. Single crystals with a diameter of 15 mm with 0.95 ⩽ x ⩽ 0.98 have been successfully grown by presaturation of the In solution zone and by taking (111) oriented GaP seeds.

Thin layers of intentionally undoped AlSb can be deposited on polycrystalline AlSb substrates from Sb solutions at low temperatures. Liquidus temperatures were measured for Sb-rich solutions below 1200 K. The eutectic was found to be at 900 ± 0.5 K at a concentration of 1.5 ± 0.5at% Al. Good initial growth conditions could be achieved using a Br 2 -ethyleneglycol solution to clean the AlSb substrates. A conventional LPE equipment using a combined sliding and tipping technique served to prepare AlSb layers. As-grown layers have a metallic lustre which is stable in air for a long time. The stability of LPE material could be improved to Bridgman material. High resolution photoluminescence spectra were detected at 1.6 K. Besides broad emission lines centred at 1.475 and 1.3 eV, a series of very sharp near band gap lines could be resolved.

In 1− x Ga x P LPE layers of x -values between x =0.7 and x =1 were grown on GaP(111)B substrates at low temperatures, ranging from 913 to 1023 K. A comparison of phase diagram calculations with growth results was made and the photoluminescence of samples of various compositions x was studied, including the position of the cross-over point x c between direct and indirect semiconduction.

InP : Yb LPE layers have been grown by a supercooling process at high growth temperatures up to 800°C. The Yb concentrations in the In growth melts ranged between 0.001 and 0.005 mole fraction. Photoluminescence and Hall measurements gave information about the incorporation behaviour of the rare earth ion Yb 3+ (4f 13 ) and about its influence on the electrical properties of InP. Time resolved photoluminescence measurements at low temperatures indicated a lifetime of about 12 μs of the excited Yb 3+ state. LPE grown InP:Yb p-n electroluminescence diodes were fabricated, which emit the intracentre Yb luminescence at 1 μm wavelength. High purity InP layers could be grown, using Yb in low concentrations to remove residual impurities from the growth melts. Net carrier concentrations N D - N A of 2 × 10 14 cm −3 at 300 K (1.5 × 10 14 cm −3 at 77 K) and carrier mobilities of 5700 cm 2 /V·s at 300 K (90,000 cm 2 /V·s at 77 K) could be achieved.

Epitaxial layers of undoped p-GaSb were grown from Ga-rich and Sb-rich solutions on (111) and (100) oriented GaSb substrates. The growth temperatures ranged from 330–470°C (Ga solution) and 635–680°C (Sb solution). Different growth results were obtained for the two LPE processes. The layers were characterized by photoluminescence measurements at low temperatures (1.8 K). The highest purity was obtained by low temperature LPE from Ga solutions.

In this paper we describe the metalorganic vapor phase epitaxial growth of InP and GaInAs with the adducts TMIn-TEP and TMGa-TEP as metal precursors. The feasibility of zone refining for the purification of metalorganic adducts to semiconductor grade is demonstrated. By taking advantage of the low vapor pressures of these adducts we have grown GaInAs-InP single and multi quantum well structures with thickness L z of the active layer down to 2.5 nm. These samples have been characterized by photoluminescence and Shubnikov-De Haas experiments.

We report the first successful growth of GaInAs‐InP multiquantum well structures by metalorganic gas phase epitaxy with adducts in one single reactor. The properties of the two‐dimensional electron gas in these samples were studied in detail by photoluminescence measurements and Shubnikov–de Haas experiments.

In0.53Ga0.47As epitaxial layers of high quality and excellent surface morphology have been grown in an automated LPE system. The growth temperature was varied between 500 and 63O°C. Room-temperature Hall measurements indicated a net carrier concentration of n = 8 × 1014 cm‾3 and mobility values of µ = 13000 cm2V‾1 s‾1 at TG 617°C and n = 7.7 × 1015 cm‾3 and μ = 9800 cm2 V‾1 s‾1 at TG = 517°C, respectively.

Two metalorganic adducts (trimethylindium-trimethylarsine (CH3)3In-As(CH3)3 and trimethylgallium-trimethylarsine (CH3)3Ga-As(CH3)3) have been used for the epitaxial growth of InxGa1−xAs on InP, and GaAs, substrates at normal pressure. Epitaxial layers with net carrier concentrations of n = 2 × 1016 cm−3, μ300K = 6600 cm2/Vs (In0.53Ga0.47As/InP) and n′ = 1 × 1016 cm−3, μ′ = 3200 cm2/Vs (In0.2Ga0.8As/GaAs) have been grown.

A new metal-organic compound, a trimethyl-indium trimethyl-phosphine adduct has been used for the growth of InP epitaxial layers. The formation of unwanted polymer products during epitaxial growth could be avoided in this way. Epitaxial layers of good quality (ND − NA≃1016−1017 cm−3 were grown at a rate of 0.8 μm/h.