Spin-flip Raman-scattering studies of compensating donor centers in nitrogen-doped zinc selenide grown by molecular-beam epitaxy

Townsley, C.; Davies, J.; Wolverson, Daniel; Boyce, P. J.; Horsburgh, G.; Steele, Timothy A.; Prior, K. A.; Cavenett, B.C.

doi:10.1103/physrevb.53.10983

Cited by 20 publications

(19 citation statements)

References 30 publications

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“…The value of g 3 ¼ 2:00 AE 0:03 is close to the free-electron value which indicates that the defect involves a classic electron trap (F center) and has been assigned by Setzler et al [14] to the singly ionised Se vacancy (V þ Se ). However, a value of g 2 ¼ 1:49 AE 0:03 has not been reported before and is significantly larger than g ¼ 1:38 AE 0:03 known for the deep donor D d in strain relaxed ZnSe : N layers [4,13]. As shown recently by Ogata et al [15] the value of g ¼ 1:38 remains surprisingly constant with increasing sulphur content and therefore with increasing strain in the layer.…”

Section: Resultsmentioning

confidence: 61%

“…The anisotropy is caused by the strain induced splitting of the valence-band related states as has been recently studied in detail [11,12]. The value of g 1 ¼ 1:10 AE 0:03 is well known for (26 meV) effective-mass like donors in ZnSe [4,13]. The value of g 3 ¼ 2:00 AE 0:03 is close to the free-electron value which indicates that the defect involves a classic electron trap (F center) and has been assigned by Setzler et al [14] to the singly ionised Se vacancy (V þ Se ).…”

Section: Resultsmentioning

confidence: 96%

“…Thus, the SFR scattering data indicate that a new donor center exists in pseudomorphically strained ZnSe : N layers embedded in ZnMgSSe barriers. [4] for hydrogenic donors in ZnSe. This points to an effectively repulsive impurity core compared to a single-charged donor center.…”

Section: Resultsmentioning

confidence: 99%

“…Beyond that, the doping behaviour of thin, fully strained ZnSe layers is largely unknown. In contrast to the commonly investigated nitrogen doping of thick, relaxed ZnSe layers [1][2][3][4][5][6] we focused on the more device relevant situation were N is incorporated in fully strained thin (QW like) layers. For this purpose the observation of the donor-acceptor-pair (DAP) recombination is a useful tool to analyze the influence of compensating donors.…”

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confidence: 99%

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Negatively Charged Donor Centers in Ultrathin ZnSe:N Layers

Strauf

Michler

Gutowski

et al. 2002

phys. stat. sol. (b)

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ZnMgSSe barriers were investigated by means of photoluminescence and spin-flip-Raman (SFR) scattering spectroscopy. A new donor-acceptor-pair (DAP) band has been observed involving a very shallow donor with a binding energy of (19 AE 2) meV and the well-known N acceptor on Se site. Further evidence for a new donor center is given by transitions in angle-dependent SFR scattering measurements which correspond to an isotropic (donor-like) g-value of (1:49 AE 0:03). The 19 meV donor is interpreted as the negatively charged state of the usually found 52 meV deep donor in ZnSe : N. This is supported by the temperature behavior of the DAP band and, further, by its pronounced appearance for resonant excitation into the barriers quite similar to the behavior of trions.Introduction One of the most important prerequisites for long lifetime optoelectronic devices such as laser diodes is crystalline perfection. Therefore, it is absolutely necessary to keep the maximum layer thickness in strained heterostructures below the critical value of strain relaxation. In ZnSe-based devices p-type doping is one of the most serious difficulties. Beyond that, the doping behaviour of thin, fully strained ZnSe layers is largely unknown. In contrast to the commonly investigated nitrogen doping of thick, relaxed ZnSe layers [1-6] we focused on the more device relevant situation were N is incorporated in fully strained thin (QW like) layers. For this purpose the observation of the donor-acceptor-pair (DAP) recombination is a useful tool to analyze the influence of compensating donors. In strain relaxed layers the incorporation of N was found to be accompanied by the formation of a shallow donor ðD s Þ of approximately 29 meV [3] binding energy and a 44-52 meV [1,3,5,7] deep donor ðD d Þ, respectively. In conjunction with the well-known N acceptor level of 110 meV [8] these donors manifest themselves through the appearance of two DAP transition band series, D s AP and D d AP. For the case of fully strained ZnSe : N layers which are embedded in ZnMgSSe barriers, we have recently found that a very shallow donor with a binding energy of (19 AE 2) meV is the dominant compensating donor while transitions involving the deep donors ðD d Þ usually found in strain-relaxed layers seem to be largely absent [9]. In this work we present further evidence for this new donor level. In addition, we propose a model in which the very shallow donor level is assigned to the negatively charged state of the deep donor D d . Negatively charged donor centers (D À ) are the immobile analogue of the mobile trion complex, and they consist of a fixed positive charge ðD þ Þ and two electrons [10].

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Section: Resultsmentioning

confidence: 61%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Negatively Charged Donor Centers in Ultrathin ZnSe:N Layers

Strauf

Michler

Gutowski

et al. 2002

phys. stat. sol. (b)

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“…15 The shallow compensating donor responsible for the presence of the D s AP bands in the PL spectra, on the other hand, has attracted very little attention and in the absence of detailed investigations it is commonly assumed to be a residual impurity in ZnSe. [7][8][9]16 Consequently, it is generally supposed that N would initially incorporate exclusively as an acceptor on Se substitutional sites, the presence of residual donors giving rise to the D s AP bands in the PL spectra. Above a carrier concentration of about 10 17 cm Ϫ3 N would get involved in the formation of deep compensating donors leading to D d AP bands taking over in the PL spectra.…”

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Self-compensation in nitrogen-doped ZnSe

et al. 1997

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Nitrogen-doped and nitrogen-implanted ZnSe epitaxial layers grown by molecular-beam epitaxy are studied through photoluminescence ͑PL͒, selective PL, and PL-excitation spectroscopies. The results are compared with those obtained from samples implanted with other impurities. All N-containing samples, and only those, give rise to transitions corresponding to a dominant shallow donor with a binding energy of 29.1 meV. This donor is not a residual impurity in ZnSe but is associated with nitrogen. We propose that it involves nitrogen located on interstitial sites. In addition, the deep compensating donor is already present in lightly doped samples. Our results demonstrate that N doping of ZnSe is accompanied by the concomitant creation of N-related defects, both shallow and deep ones, from the onset of doping. An inescapable dramatic compensation of N acceptors ensues. ͓S0163-1829͑97͒51728-0͔The doping properties of wide-band-gap semiconductors are currently under focus driven by both the perspective to fabricate efficient short-wavelength optoelectronic devices and the aim to elucidate the intricate processes at work on a microscopic scale during doping and/or carrier compensation. ZnSe is a particularly enticing material in this respect since its p-type doping has been challenging for decades. 1,2 Indeed, only recently did plasma-activated nitrogen emerge as the ͑still͒ unique dopant suitable for the growth of p-type ZnSe by molecular-beam epitaxy ͑MBE͒, 3,4 which remains the only technique allowing to reproducibly grow stable p-type ZnSe films. The highest free-hole concentration reported so far is N a ϪN d ϳ1 -2ϫ10 18 cm Ϫ3 . 5 N-doped layers, however, are always at least partially compensated, even at low doping levels. 6 Compensation manifests itself in the low-temperature photoluminescence ͑PL͒ spectra of ZnSe:N layers by the presence of two distinct series of donor-acceptor pair ͑DAP͒ bands. 7-9 The first series, D s AP, with a zero-phonon line at about 2.70 eV arises from recombinations between a shallow donor ͑D s ͒ and the nitrogen acceptor, while the second series, D d AP, with a zero-phonon line at about 2.68 eV arises from recombinations between a deep donor ͑D d ͒ and the nitrogen acceptor. [7][8][9] Most studies of carrier compensation in ZnSe:N material have focused up to now on the deep compensating donor. Many theoretical models have been proposed 10-13 but experimental results agree well with a deep donor consisting of a N-related complex involving Se vacancies. 7,9,14 We have precisely determined its electronic structure and deduced a binding energy of 45.2Ϯ0.3 meV. 15 The shallow compensating donor responsible for the presence of the D s AP bands in the PL spectra, on the other hand, has attracted very little attention and in the absence of detailed investigations it is commonly assumed to be a residual impurity in ZnSe. 7-9,16 Consequently, it is generally supposed that N would initially incorporate exclusively as an acceptor on Se substitutional sites, the presence of residual donors giving ris...

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Spin‐flip Raman scattering studies of antimony‐doped ZnSe

Davies

Wolverson

Aliev

et al. 2004

Physica Status Solidi (b)

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Spin-flip Raman scattering and photoluminescence studies of ZnSe crystals doped with antimony have provided evidence for the presence of (i) a shallow acceptor level at about 70 meV above the valence band and (ii) a previously unreported deep donor level at about 55 meV below the conduction band, with a gvalue of 1.81. As in ZnSe:N, it is possible that the formation of such deep-donor states may be an inevitable consequence of high concentrations of p-type dopants and the resulting compensation may be one of the reasons why attempts to obtain p-type conductivity continue to be difficult. The deep donor g-value fits well into the sequence of previously reported g-values of 1.11, for shallow donor centres (at about 26 meV), of 1.38 for donors at about 45 meV and of 2.00 for deep donors at 90 meV.

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Spin-flip Raman-scattering studies of compensating donor centers in nitrogen-doped zinc selenide grown by molecular-beam epitaxy

Cited by 20 publications

References 30 publications

Negatively Charged Donor Centers in Ultrathin ZnSe:N Layers

Negatively Charged Donor Centers in Ultrathin ZnSe:N Layers

Self-compensation in nitrogen-doped ZnSe

Spin‐flip Raman scattering studies of antimony‐doped ZnSe

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