Carbon diffusion in undoped, n-type, and p-type GaAs

Abstract

The effects of background doping, surface encapsulation, and As4 overpressure on carbon diffusion have been studied by annealing samples with 1000 Å p-type carbon doping spikes grown within 1 μm layers of undoped (n−), Se-doped (n+), and Mg-doped (p+) GaAs. The layers were grown by low-pressure metalorganic chemical vapor deposition using CCl4 as the carbon doping source. Two different As4 overpressure conditions were investigated: (1) the equilibrium pAs4 over GaAs (no excess As), and (2) pAs4 ∼2.5 atm. For each As4 overpressure condition, both capless and Si3N4-capped samples of the n−-, n+-, and p+-GaAs crystals were annealed simultaneously (825 °C, 24 h). Secondary-ion mass spectroscopy was used to measure the atomic carbon depth profiles. The carbon diffusion coefficient is always low, but depends on the background doping, being highest in Mg-doped (p+) GaAs and lowest in Se-doped (n+) GaAs. The influence of surface encapsulation (Si3N4) and pAs4 on carbon diffusion is minimal.

Growth aspects of AlGaAs/GaAs tunnel diodes for multijunction solar cells

“…Starting from these considerations, it should be clear that it is crucial to select dopants with low diffusion coefficient and to reduce as much as possible the growth temperature and growth cycle. Among P-type dopants for III-V semiconductors, carbon has attracted large attention because of its low diffusion coefficient and high solubility [2][3][4]. The incorporation of C atoms has been obtained in different way.…”

Implantation of Carbon in GaAs and Compensating Native Defects

“…Its diffusion coefficient is significantly lower [2] than that of group II p-type dopants such as Mg and 2n. [3, 4J Ultra-high doping levels (p>1020 cm-3 ) have been attained with epitaxial growth.…”

Improved AlGaInP-based red (670–690 nm) surface-emitting lasers with novel C-doped short-cavity epitaxial design

“…[10][11][12] The relative positions of the Al x Ga 1Ϫx As and (Al y Ga 1Ϫy ) 0.5 In 0.5 P band edges are also given. By using an appropriate intermediate a͒ Electronic mail: rpschne@sandia.gov AlAs y P 1Ϫy composition, the valence band offset between AlAs and AlGaInP can be graded in a pseudocontinuous manner for all (Al y Ga 1Ϫy )InP compositions in the range yϭ0.5-1.0, [8][9][10] and this layer may even contribute to improved carrier confinement. The small tensile strain can be accommodated in a sufficiently thin layer ͑р10 nm͒ to avoid relaxation.…”

“…Previous reports of AlGaInP/ AlGaAs heterostructure laser diodes have all employed Zn or Mg doping on the p side of the junction to improve hole injection, 5,6 eliminating a potential key advantage of the use of AlGaAs and further complicating dopant diffusion characteristics. 7,8 Such difficulties have led to implementation of relatively thick ͑8 ͒ optical cavities in red VCSELs 6 at the cost of increased optical loss and thermal resistivity and less efficient current constriction.In the present letter we investigate a modified epitaxial design that not only enables straightforward implementation of short ͑1 wave͒ optical cavities but also the use of carbon as the sole p-type dopant in AlGaInP/AlGaAs-based red EELs and VCSELs. This approach better utilizes the advantages of AlGaAs materials technology in the device structure and eliminates the problems with Zn and Mg doping entirely.…”

“…Previous reports of AlGaInP/ AlGaAs heterostructure laser diodes have all employed Zn or Mg doping on the p side of the junction to improve hole injection, 5,6 eliminating a potential key advantage of the use of AlGaAs and further complicating dopant diffusion characteristics. 7,8 Such difficulties have led to implementation of relatively thick ͑8 ͒ optical cavities in red VCSELs 6 at the cost of increased optical loss and thermal resistivity and less efficient current constriction.…”