Effects of thermal annealing on deep-level defects and minority-carrier electron diffusion length in Be-doped InGaAsN

Abstract

We report the effects of ex situ thermal annealing on the deep-level defects and the minority-carrier electron diffusion length in Be-doped, p-type In0.03Ga0.97As0.99N0.01 grown by solid source molecular-beam epitaxy. Deep-level transient spectroscopy measurements reveal two majority-carrier hole traps, HT1 (0.18 eV) and HT4 (0.59 eV), and two minority-carrier electron traps, ET1 (0.09 eV) and ET3 (0.41 eV), in the as-grown sample. For the sample with postgrowth thermal annealing, the overall deep-level defect-concentration is decreased. Two hole traps, HT2 (0.39 eV) and HT3 (0.41 eV), and one electron trap, ET2 (0.19 eV), are observed. We found that the minority-carrier electron diffusion length increases by ∼30% and the leakage current of the InGaAsN∕GaAsp-n junction decreases by 2–3 orders after thermal annealing. An increase of the net acceptor concentration after annealing is also observed and can be explained by a recently proposed three-center-complex model.

The effects of quantum well numbers and thermal annealing on optical properties of GaInNAs/GaAs quantum well structures

“…They also found that deep levels may appear after annealing at about 700 o C. Since our samples are also annealed at 700 o C, appearance of the traps is not surprising after the thermal annealing. The observed energy level with 0.1eV activation energy is also observed by Xie et al using DLTS technique [9] and ascribed for an electron trap level.…”

“…Of the observed trap levels, the traps having the 0.16 eV, 0.18 eV, and 0.3 eV activation energies have already been observed in GaInNAs/GaAs system using similar techniques [5,9,10] Contributed Article [11,12]. They also found that deep levels may appear after annealing at about 700 o C. Since our samples are also annealed at 700 o C, appearance of the traps is not surprising after the thermal annealing.…”

Molecular beam epitaxy growth of bulk GaNAsSb on Ge/graded-SiGe/Si substrate

“…However, this effort had initially suffered from the difficulty in growing high quality, smooth surface morphology and thick (41 mm) 1-1.3 eV nitride materials, namely the Ga 1Ày In y N x As 1Àx layer with y=3x [7]. Success was also limited by the short minority carrier lifetime in bulk GaInNAs materials due to the presence of deep level traps [8]. In order to avoid the detrimental effect of In-N clustering and to embrace the beneficial effect of Sb in possibly reducing N migration, and hence suppressing the formation of N-complex, the GaNAsSb material was investigated [8][9][10][11].…”

“…Success was also limited by the short minority carrier lifetime in bulk GaInNAs materials due to the presence of deep level traps [8]. In order to avoid the detrimental effect of In-N clustering and to embrace the beneficial effect of Sb in possibly reducing N migration, and hence suppressing the formation of N-complex, the GaNAsSb material was investigated [8][9][10][11]. To the best of our knowledge, this is the first nitrogenplasma-assisted molecular beam epitaxy (MBE) growth demonstration of GaNAsSb on the Ge/graded-SiGe/Si substrate.…”

III–V dilute nitride-based multi-quantum well solar cell

“…In particular, various schemes, involving the use of $1.0-1.25 eV GaInNAs subcells, have been devised to enhance the efficiency of existing triple and quadruple junction solar cells [2]. Nevertheless, thus far, poor minority carrier properties [3,4] and doping issues [5,6] associated with thick bulk-like dilute nitrides have hindered the success of these approaches [7][8][9][10][11].…”