Nitrogen: Not a Dopant in Crystalline Si (C-Si), But an N-Type Dopant in A-Si:H, Why?

1994 ◽  
Vol 336 ◽  
Author(s):  
G. Lucovsky ◽  
M.J. Williams ◽  
S.S. He ◽  
S.M. Cho ◽  
Z. Jing ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Chemical Bonding ◽  
Nearest Neighbor ◽  
Hydrogenated Amorphous Silicon ◽  
Statistical Association ◽  
Ir Studies ◽  
Local Bonding ◽  
Bonding Properties ◽  
Hydrogenated Amorphous

ABSTRACTWe have incorporated N-atoms into hydrogenated amorphous silicon in the Si-rich alloy regime to ∼12 at.% N, and have observed a transition from n-type doping to alloying as the concentration of N-atoms is increased above about 5 at.%. By analogy with the local bonding arrangements of P-donors in n-doped a-Si:H, we attribute the doping to four-fold coordinated N-atoms with second neighbor H-atoms as in N+-Si-H linkages. The occurrence of these arrangements is supported by (i) IR studies which indicate a non-statistical association of N and H-atoms bonded to the same Si-atom, and (ii) a chemical bonding model in which the large effective electronegativies of four-fold coordinated N+ atoms and neutral O-atoms promote similar bonding properties with respect to their nearest-neighbor arrangements with Si and H atoms such as N+ (O) -Si-H linkages

Local bonding arrangements of boron in doped hydrogenated amorphous silicon

1984 ◽  
Vol 56 (6) ◽  
pp. 1874-1877 ◽  
Author(s):  
S. G. Greenbaum ◽  
W. E. Carlos ◽  
P. C. Taylor
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Local Bonding ◽  
Hydrogenated Amorphous

Electronic Structure of Compensated Dopants in Hydrogenated Amorphous Silicon

1989 ◽  
Vol 149 ◽  
Author(s):  
L. H. Yang ◽  
C. Y. Fong
Keyword(s):  
Amorphous Silicon ◽  
Boron Atom ◽  
Phosphorus Atom ◽  
Nearest Neighbor ◽  
Energy State ◽  
Hydrogenated Amorphous Silicon ◽  
Local Environment ◽  
Realistic Model ◽  
Strong Localization ◽  
Hydrogenated Amorphous

ABSTRACTWe use first principles pseudopotential method to study the electronic structures of compensated dopants in a realistic model of hydrogenated amorphous silicon. Boron and phosphorus atoms are treated as dopants. Two states in the gap are identified as the boron-phosphorus pair related states. The lower energy state, strongly localized around the boron atom, is obtained when the atom has a hydrogen atom as a nearest neighbor. The local environment does not affect the localization feature of the state. Other environment around the boron atom cause the charge distribution to be more extended in space. The higher energy state having its charge around the phosphorus atom does not show, strong localization at the phosphorus atom.

Structural Equilibration in Pure and Hydrogenated Amorphous Silicon

1993 ◽  
Vol 297 ◽  
Author(s):  
Gerhard Müller ◽  
Gerhard KrÖtz
Keyword(s):  
Amorphous Silicon ◽  
Degrees Of Freedom ◽  
Crystalline Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Electronic System ◽  
Relaxation Processes ◽  
Electrochemical Processes ◽  
Local Bonding ◽  
Defect Sites ◽  
Hydrogenated Amorphous

Chemically pure (a-Si) and hydrogenated amorphous silicon (a-Si:H) are metasta- ble materials which are thermodynamically unstable with respect to crystalline silicon (c-Si). In both materials, however, partial thermal equilibria can be established between certain structural, configurational and electronic degrees of freedom. The present paper discusses experiments on both amorphous (a-) materials showing that two kinds of structural change can take place within random Si networks: structural relaxation and configurational equilibration. The first process can be observed in both materials indicating that it is supported by intrinsic degrees of freedom of the random Si networks. During these changes partial thermal equilibria between distorted and broken bonds are established via irreversible and relatively long-range relaxation processes. The second kind of change can only be observed in a-Si:H, indicating that it is H-related. The H-related degrees of freedom support reversible valence alternation reactions in which the local bonding configuration of the dopant and defect sites is changed and in which their charge states are altered. These latter interactions establish a strong coupling between the electronic system and the configurational degrees of freedom of the random Si networks. Formally, these latter changes bear strong similarity to the electrochemical processes that take place in liquid electrolytes.

ESR and IR Studies on B-Doped Hydrogenated Amorphous Silicon-Nitrogen Film

1986 ◽  
Vol 96 (2) ◽  
pp. K187-K189 ◽  
Author(s):  
Chen Guanghua ◽  
Zhen Chenzhi ◽  
Zhang Fangqing ◽  
Cheng Jinlong ◽  
Chen Wei
Keyword(s):  
Amorphous Silicon ◽  
Hydrogenated Amorphous Silicon ◽  
Ir Studies ◽  
Hydrogenated Amorphous

Voids in Hydrogenated Amorphous Silicon: A Comparison of ab initio Simulations and Proton NMR Studies

2008 ◽  
Vol 1066 ◽  
Author(s):  
Sudeshna Chakraborty ◽  
David C Bobela ◽  
P C Taylor ◽  
D. A. Drabold
Keyword(s):  
Ab Initio ◽  
Amorphous Silicon ◽  
Nearest Neighbor ◽  
Hydrogenated Amorphous Silicon ◽  
Simulation Methods ◽  
Hydrogen Atoms ◽  
Nmr Studies ◽  
Ab Initio Simulations ◽  
Nmr Data ◽  
Hydrogenated Amorphous

ABSTRACTRecently, a new hydrogen NMR signal has been observed in a number of PECVD prepared hydrogenated amorphous silicon (a-Si:H) films of varying quality. It is speculated that the signal is the consequence of a dipolar-coupled hydrogen pair separated, on average, by 1.8 ± 0.1 Å. To elucidate the possible bonding configurations responsible for the NMR data of ref. [1], we have used ab initio simulation methods to determine a set of relaxed structures of a-Si:H with varying void sizes and H-concentrations. Models containing two isolated hydrogen atoms indicate a preferred H-H distance of approximately 1.8 Å when the two atoms bond to nearest neighbor silicon atoms. This separation also occurs for models containing small, hydrogenated voids, but the configurations giving rise to this H-H distance do not appear to be unique. For larger voids, a proton separation of about 2.4Å is seen, as noted previously [2]. There appears to be consistency between the computed structures and the NMR data for configurations consisting of isolated hydrogen pairs or for clusters of an even number of hydrogen atoms with the constraint that the average H-H distance is 1.8 Å. In this paper, we will discuss the most probable bonding configurations of clustered hydrogen based upon the extent of the NMR data and simulated structures.

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