B. W. Liang

Electrical properties of InP grown by gas‐source molecular beam epitaxy at low temperature

InP grown by gas‐source molecular beam epitaxy at low temperature has been studied by Hall effect and admittance spectroscopy measurements. Contrary to GaAs, InP grown at low temperature is n‐type and has low resistivity. The electron concentration of InP increases dramatically with decreasing growth temperature. A deep level at Ec−ED=320±50 meV is found to be the dominant donor in InP grown at low temperature.

A kinetic model for As and P incorporation behaviors in GaAsP grown by gas‐source molecular beam epitaxy

A kinetic model has been developed to explain As and P incorporation behaviors in GaAs1−xPx epilayers grown on GaAs (001) by gas‐source molecular beam epitaxy. The model can predict the P compositions for various substrate temperatures and flow rates. The model shows that an in situ determination of GaP molar fraction in GaAs1−xPx can be performed by group V‐induced intensity oscillations of reflection high‐energy‐electron diffraction at low substrate temperatures where desorption of group V species is negligible. At high substrate temperatures the compositions can be determined from the arsine and phosphine flow rates.

Determination of V/III ratios on phosphide surfaces during gas source molecular beam epitaxy

Phosphorus‐controlled growth rate of homoepitaxial (100) InP, GaP, and AlP on GaP substrates by gas source molecular beam epitaxy was investigated. Elemental group‐III sources and thermally cracked phosphine were used. The growth rate was monitored by the specular beam intensity oscillations of reflection high‐energy electron diffraction. This technique gives exact values of V/III ratio on the surface by measuring the amount of phosphorus which is actually incorporated into the film. Here the V/III ratio is defined as P‐controlled growth rate divided by group‐III‐controlled growth rate instead of the beam flux V/III ratio. Also the phosphorus surface desorption activation energies were measured to be 0.61 eV and in the range between 0.89 and 0.97 eV for InP and GaP, respectively.

In situ determination of phosphorus composition in GaAs1−xPx grown by gas‐source molecular beam epitaxy

We report for the first time an in situ determination of phosphorus compositions in a mixed group‐V compound, such as GaAs1−xPx, grown by gas‐source molecular beam epitaxy. Reflection high‐energy electron diffraction intensity oscillations from As‐limited and (As+P)‐limited growth are observed on a Ga‐rich GaAs surface. The phosphorus composition is therefore deduced from the different growth rates. Viability of this technique is strongly confirmed by the good agreement with the phosphorus compositions determined ex situ by x‐ray rocking curve measurements on GaAs/GaAsP strained‐layer superlattice structures.

ORIGIN OF N-TYPE CONDUCTIVITY OF LOW-TEMPERATURE GROWN INP

It is shown with correlated magnetic resonance and electrical measurements that the PIn antisite is the prevailing defect in InP grown by molecular‐beam epitaxy at low temperature. The first ionization level of the PIn antisite is resonant with the conduction band, which makes the material n‐type conducting due to autoionization of the PIn antisite.

A study of group-V element desorption from InAs, InP, GaAs and GaP by reflection high-energy electron diffraction

Abstract Desorption behavior of arsenic on InAs and GaAs, and phosphorus on InP and GaP surfaces has been studied by the specular-beam intensity change of reflection high-energy electron diffraction when the group-V-cracker shutter is closed during growth interruption (group-III shutter closed) in gas-source molecular-beam epitaxy. We obtained an activation energy of 55 kcal/mol for arsenic desorption from InAs at high temperatures, and 38 kcal/mol at low temperatures. This differences is explained. Compared with arsenic on InAs, phosphorus on InP has a very large desorption rate constant at high temperatures and only one activation energy of 50 kcal/mol. For GaAs and GaP, the desorption activation energy for arsenic on GaAs is 58 kcal/mol, phosphorus on GaP 43 kcal/mol.

Electronic properties of low-temperature InP

We have investigated InP layers grown by low-temperature (LT) gas source molecular beam epitaxy. Using high-pressure hall effect measurements, we have found that the electronic transport in the LT epilayers is determined by the presence of the dominant deep donor level which is resonant with the conduction band (CB) located 120 meV above the CB minimum (ECB). We find that its pressure derivative is 105 meV/GPa. This large pressure derivative reveals the highly localized character of the donor which via auto-ionization gives rise to the high free electron concentration n. From the deep level transient spectroscopy and Hall effect measurements, we find two other deep levels in the band gap at ECB−0.23 eV and ECB−0.53 eV. We assign the two levels at ECB 0.12 eV and ECB−0.23 eV to the first and second ionization stages of the phosphorus antisite defect.

Surface kinetics of chemical beam epitaxy of GaAs

A new kinetic model for chemical beam epitaxy of GaAs using triethylgallium and arsine is proposed. Both group III and group V species are equally important in the surface reactions. This model can fit experimental data very well. Various aspects of the growth rate as a function of substrate temperature, triethylgallium and arsine flow rates are examined.

Heavily carbon-doped p-type GaAs and In0.53Ga0.47As grown by gas-source molecular beam epitaxy using carbon tetrabromide

Highly p-type carbon-doped GaAs and In 0.53 Ga 047 As grown by gas-source molecular beam epitaxy were obtained by using carbon tetrabromide as the carbon source. In the low 10 19 cm -3 range almost all carbon atoms are electrically active in GaAs, and at least 85% of the carbon atoms are activated at a concentration as high as 1.2×10 20 cm -3 . A hole concentration of 9×10 19 cm -3 in In 0.53 Ga 0.47 As, among the highest reported to date, was achieved. No hydrogenation problem was observed

A study of Ar ion laser-assisted metalorganic molecular beam epitaxy of GaAs by reflection high-energy electron diffraction

Abstract The growth behavior of Ar-ion-laser-assisted metalorganic molecular beam epitaxy (MOMBE) of (001) GaAs, in the temperature range 330–450°C with triethylgallium (TEGa) and As 4 , was studied by monitoring the specular-beam intensity oscillations of reflection high-energy electron diffraction (RHEED), with the laser turned on and off. The decomposition rate of TEGa is enhanced under Ar + laser irradiation. The Ar + laser also enhances the surface migration of adsorbates and arsenic desorption. In the arsenic-controlled growth regime, the growth rate increases monotonically at low laser power and tends to saturate at high laser power due to a balance between enhanced decomposition of TEGa and desorption of arsenic.