Correlation between arsenic precipitates and vacancy-type defects in low-temperature-grown GaAs

Abstract

We have utilized x-ray photoelectron and variable energy positron beam spectroscopies for deplh profiling excess arsenic. arsenic precipitates. and vacancy-type defects in GaAs grown by molecular beam epitaxy at low temperatures (LT-G~As). XPS results show about 1.3% excess arsenic in as-grown LT-G~As and a non-uniform depth profile of arsenic Concentration in annealed LT-G~As. Doppler broadening of the positron-electron annihilation radiation (S parameter) reveals a non-uniform depth profile of defects in annealed LT-G~As. We observe a clear comlation between the depth profile of the S parameter and As in annealed LT-GAS.Molecular beam epitaxy (MBE) GaAs grown at low temperatures (LT-GaAs) has been the

Defect identification in GaAs grown at low temperatures by positron annihilation

“…10 7 coincident events were recorded for each spectrum. The intensity of the annihilation with high-momentum core electrons was characterized by a W parameter calculated in the momentum range (15)(16)(17)(18)(19)(20)…”

“…36 Lattice relaxations were not taken into account. Theoretical W parameters are obtained from the calculated momentum distribution also in the range (15)(16)(17)(18)(19)(20)…”

“…The positron lifetime and conventional Doppler-broadening measurements discussed earlier provide only the information that these positron traps have an open volume comparable to small vacancy clusters, i.e., they are not Ga monovacancies. It has been suggested that these defects are associated with As precipitates 20 but it has often been assumed that these are just isolated vacancy clusters. 10,11 In Fig.…”

“…9,19 Positron annihilation results indicate the formation of defects larger than monovacancies during annealing. 10,11 It has been suggested that positron trapping in annealed LT-GaAs is related to As precipitates 20 whereas other authors interpreted their results in terms of isolated vacancy clusters. 10 The use of LT-GaAs for different applications requires a proper understanding of the defects which determine the properties of the material.…”

Effect of column III vacancy on arsenic precipitation in low-temperature grown III–V arsenides

“…Positron annihilation spectroscopy has revealed that there exist a large number of monovacancies in the as-grown film but vacancy clusters in the annealed LT-GaAs. [7][8][9][10] In other words, the vacancies redistribute when annealed. On the other hand, excess As redistributes when LT-GaAs is annealed.…”