Models of deep centres in gallium phosphide

Abstract

The effects of varying the ammonia flux on the concentrations of background Si and free carriers and on deep traps for majority and minority carriers in n-GaP layers grown by vapour epitaxy have been studied by secondary ion mass spectrometry and deep level transient spectroscopy. The contribution from the background silicon to the free carrier concentration in samples variously doped with nitrogen is discussed. It is shown that the deep centre at E c − 0.24 eV may be attributed to silicon. The model of this centre in the form Si Ga -V P accounts for experimental results obtained in the present work and those already reported. The concentration of the dominant nonradiative recombination centre at E v + 0.75 eV is studied, depending on growth conditions, and its model is proposed in the form of a complex consisting of intrinsic defects.

Deep Level Studies in High-Resistive Gallium Phosphide Single Crystals

“…The energy level has been reported by many workers with a varying degree of accuracy, E C − 0.22 eV 25 to E C − 0.27 eV. 26 The electron trap T2 located at E C − 0.32 eV has been reported by many workers, [22][23][24]27 to be situated at 0.28 ± 0.02 eV below the conduction band minima. However, no suitable model has been found yet to identify the nature or structure of this trapping center.…”

“…Electron trap center T3 located at E C − 0.39 eV has been reported to be found in nitrogen doped GaP. 22 The fourth trap center T4 located at E C − 0.62 eV Figure 6 shows a CTS scan obtained in the temperature range 85 -300 K for a Ni-GaP Schottky junction and the defect parameters extracted are summarized in Table III. Two well-defined peaks were observed in the CTS scan corresponding to two different defect levels.…”

“…The defect level corresponding to peak # 1 has an activation energy of 0.26 eV identified by Popov et al, 21 as an electron trap center T1 (E C − 0.26 eV) arising due to iron gallium antisite vacancy complex. The same defect level has also been identified as phosphorus vacancy (V P ) in the crystal lattice 22,23 and later due to as a combination of silicon impurities from the quartz ampoule used for the crystal growth and V P . 24 Since the sample is doped with Fe, Fe related defects or their complexes is more likely to be found.…”

Controlled vapor-pressure heat-treatment effect on deep levels in liquid-encapsulated czochralski-grown GaP crystals

“…[7][8][9][10] Our discussion, based on results of PHCAP measurements, reveals the existence of some deep levels originating from nonstoichiometric point defects. Electron traps of E C Ϫ1.1 eV, E C Ϫ1.6 eV, E C Ϫ1.9 eV, and a hole trap of E V ϩ2.26 eV are mainly detected.…”

Defect properties of solar cells with layers of GaP based dilute nitrides grown by molecular beam epitaxy

“…This defect was also observed in undoped GaP:N layers grown by vapor phase epitaxy. 23 At temperatures above 160 K, the capacitance is almost independent of the frequency and slowly increases with heating up to 360 K, so there is no response from defect levels in the explored temperature range. Therefore, admittance spectroscopy allowed us to detect defects with low activation energy that can be associated with silicon incorporation in dilute nitrides and can be responsible for unintentional doping of these layers.…”