Investigation of the density of localized states in a-Si using the field effect technique

Madan, A.; Comber, P. G. Le; Spear, W. E.

doi:10.1016/0022-3093(76)90134-4

Cited by 368 publications

(40 citation statements)

References 19 publications

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“…Many of these products are made with thin fi lms. Liquid-crystal displays 1 are driven by active matrices of amorphous silicon transistors, 2 and 10% of all solar cells are made of amorphous silicon 3 or chalcogenide fi lms. 4,5 Like any other stiff material, circuits become fl exible and rollable when their thickness is reduced to 1/1000 of the desired radius of curvature.…”

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confidence: 99%

Materials for stretchable electronics

2012

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Materials for stretchable electronics

2012

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“…30). There appear to be two peaks in the density of states in the gap, one 0.4 eV below the conduction-band edge and another about 0.4 eV above the valence-band edge (29).…”

Section: F Photostructural Cl?angesmentioning

confidence: 97%

“…A typical effect is photodarkening, apparently resulting from a broadening of the Urbach tail, but optically induced crystallization of the glass has also been observed (28). prepared by ordinary techniques exhibit only a very small field effect (29), leading to the conclusion that the density of localized states in the gap is of the order of lo1' ~r n -~ or greater. However, the glow-discharge-deposited samples, especially those deposited on a high-temperature substrate, have a much larger field effect, providing evidence for a considerably smaller localized-state density, of the order of 1017 c~n -~ (29.…”

Section: F Photostructural Cl?angesmentioning

confidence: 99%

Localized electronic states in amorphous semiconductors

Adler¹,

Yoffa²

1977

Can. J. Chem.

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AVID A~~~~ and ELLEN 3. YOFFA. Can. j. Chern. 95. I920 (1977). The experimental results pertaining to the electronic structure of covaient amcrphoi~s semiconductors are briefly reviewed. It is found that three classes of materials exist, depending on the lowest-energy coordinatiofi of the predominant cheinicai component. In each case, the iransport properties are ordinarily conirolled by the Iocalized states in the gap resulting froin the minimum-mergy defect sites, in which the local coordination is not optimal for certain atoms. These :ocalized states are treated in terms of a Hubbard inodei, in whish the effective repulsion between two electrons simuitaneously resent on the same center is taken as positive for tetrahedrally bonded solids and negative for chaisogenide and pniciide glasses. The electronic struclure is discussed in detail. lt is shown that even such a simple model can account for almost ail of the experimental properties of the major classes of amorphoiis semiconductors. Chem. 55. i920 (1977). On passe brievement en revue ies rCsu1tats exptrimentaux se rapportant a la structure tlecironique de serniconducte~!rs amorphes covalents. On a trouvi qu'il existe trois classes de n-iateriaux en fonction de l'knergie ia plus basse ae coordination pour le compose chirnique ?rtdominant. Dans chaque cas, ies proprietts de transport sont ordinairenlent controiees par des ktats Iocalists dans le fcsse resultant des sites de dkfauts d'energie minimum dans iesquels la coordination locale n'est pas optimaie pour ccrtains atcmes. On traitc ccs crats localisks en terrnes du modeie de Hi~bbard dans Zequel ia rkpuision efictive entre deux electrons presents d'iine facon simultanee sur le mEme centre est considtree comme positive pour les solides lies d"une facon tetraedrique et negative pour les verres chaicogknides et pnictides. 0 1 7 discute en iiitail de la structure electronique. On montre que mime un rnodile aussi sinlple peut rendre cornpie de pratiquement routes les proprietis expirimentales des classes majeurs des semi canducteurs amorphes.[ progress in Llnderstandiiag the,r eiectrcnic These inciude not only the Group %V atoms: such bas coilreAs is -the case hr the as Ge a116 Si, but also the Grocp i 11-V materials. corresponciing crSrstzlline solids. both suchas GaAs, and Inore cornpiex solids with an and icllis anorphous exist (1). a""' "' %"aIence of fol~r: such as cdGeAs2. Because onlly *he former materials have been 'ntermedlate beiween these tlvo major ciasses suficientiy physical be-are 'he pt7ictideies: which contaii~ predominantly havior can be understood iia some detail, we the Group V atoms, Sb, As, or P.shall concentrate on them in this paper.in this paper, we analyze ":he experimentalThree major of covaient amorphous resuitson these main groups of covalent amorsolids be differentiated, depending on the phous se~l~isofiductor~. znd sun?.rnasize a mode! chemical of the constituent F r their eiectronic structure which appears to a,ecms. the most intensively inveseigated 5 e i i 1 a " g e a n e n t ...

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“…This material has been intensively studied worldwide involving thousands of researchers and the work of Spear [5,6] and LeComber [7][8][9], among others, have been central references. To these studies we have to add the earlier work of Madan et al [10] in determining the density of localized states that not only supported the development of high grade electronic quality undoped amorphous silicon for device applications, but also was the precursor in the use of amorphous silicon in field effect transistors [11]. Since then the main bottleneck has been the inherent light degradation of a-Si:H [12] and the low carrier mobility which prevents even larger application potential of the material.…”

Section: Introductionmentioning

confidence: 99%