Doped polymer semiconductors with ultrahigh and ultralow work functions for ohmic contacts

Nature ◽  
2016 ◽  
Vol 539 (7630) ◽  
pp. 536-540 ◽  
Author(s):  
Cindy G. Tang ◽  
Mervin C. Y. Ang ◽  
Kim-Kian Choo ◽  
Venu Keerthi ◽  
Jun-Kai Tan ◽  
...  
Keyword(s):  
Ohmic Contacts ◽  
Polymer Semiconductors ◽  
Work Functions ◽  
Doped Polymer

Bulk ion-clustering and surface ion-layering effects on work function of self-compensated charged-doped polymer semiconductors

2020 ◽  
Vol 7 (4) ◽  
pp. 1073-1082 ◽  
Author(s):  
Mervin Chun-Yi Ang ◽  
Cindy Guanyu Tang ◽  
Qi-Mian Koh ◽  
Chao Zhao ◽  
Qiu-Jing Seah ◽  
...  
Keyword(s):  
Work Function ◽  
Charge Injection ◽  
Polymer Semiconductors ◽  
Material Systems ◽  
Doped Polymer

Self-compensated hole- and electron-doped polyelectrolytes can afford 0.1 eV tuning steps in work function of charge injection/collection layers through the tethered anions. These material systems are further immune to ‘dopant’ migration.

A new insight for ohmic contacts to MoS2: by tuning MoS2 affinity energies but not metal work-functions

2017 ◽  
Vol 19 (38) ◽  
pp. 26151-26157 ◽  
Author(s):  
Qian Wang ◽  
Bei Deng ◽  
Xingqiang Shi
Keyword(s):  
Transition Metal ◽  
Ohmic Contacts ◽  
Transition Metal Dichalcogenides ◽  
Two Dimensional ◽  
Metal Dichalcogenides ◽  
Work Functions ◽  
Metal Work

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have recently attracted tremendous interest for fundamental studies and applications.

Graphene Ohmic Contacts to n-Type Silicon Carbide (0001)

2015 ◽  
Vol 821-823 ◽  
pp. 933-936 ◽  
Author(s):  
Stefan Hertel ◽  
Andreas Finkler ◽  
Michael Krieger ◽  
Heiko B. Weber
Keyword(s):  
Thermal Decomposition ◽  
Silicon Carbide ◽  
Contact Resistance ◽  
Buffer Layer ◽  
Ohmic Contacts ◽  
Specific Contact Resistance ◽  
Monolayer Graphene ◽  
Specific Contact ◽  
Order Of Magnitude ◽  
Work Functions

Epitaxial graphene on silicon carbide (SiC) can easily be grown by thermal decomposition. A well-defined epitaxial interface between graphene and substrate is formed, especially when the silicon face of hexagonal polytypes is employed. It is found that as-grown monolayer graphene with interfacial buffer layer provides perfectly ohmic contacts to n-type SiC – even to low-doped epitaxial layers without contact implantation. Contact resistances to highly doped samples are competitive with conventional annealed nickel (Ni) contacts; a direct comparison of Ni and graphene contacts on 4H-SiC resulted in an one order of magnitude reduction of the contact resistance in the case of graphene contacts. On highly doped 6H-SiC, a specific contact resistance as low asρC= 5.9·10-6Ωcm2was found. This further improvement compared to 4H-SiC is assigned to better matching of work functions at the Schottky-like interface.

Microstructural Characterization of Au-Ge-Ni based ohmic contacts to GaAs/AlGaAs modfet device

1987 ◽  
Vol 45 ◽  
pp. 326-327
Author(s):  
A.K. Rai ◽  
A.K. Petford-Long ◽  
A. Ezis ◽  
D.W. Langer
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Microstructural Characterization ◽  
Almost Everywhere ◽  
Spacer Layer ◽  
Good Contact ◽  
The Relationship ◽  
Lower Contact

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.

Microstructure of sputter deposited Ni-Sb ohmic contacts on GaAs

1989 ◽  
Vol 47 ◽  
pp. 450-451
Author(s):  
S. Yegnasubramanian ◽  
V.C. Kannan ◽  
R. Dutto ◽  
P.J. Sakach
Keyword(s):  
High Performance ◽  
Ohmic Contacts ◽  
Surface Defects ◽  
Pure Metal ◽  
Device Fabrication ◽  
Native Oxide ◽  
Metal Thin Films ◽  
Recent Developments ◽  
Different Temperatures ◽  
Sputter Deposited

Recent developments in the fabrication of high performance GaAs devices impose crucial requirements of low resistance ohmic contacts with excellent contact properties such as, thermal stability, contact resistivity, contact depth, Schottky barrier height etc. The nature of the interface plays an important role in the stability of the contacts due to problems associated with interdiffusion and compound formation at the interface during device fabrication. Contacts of pure metal thin films on GaAs are not desirable due to the presence of the native oxide and surface defects at the interface. Nickel has been used as a contact metal on GaAs and has been found to be reactive at low temperatures. Formation Of Ni2 GaAs at 200 - 350C is reported and is found to grow epitaxially on (001) and on (111) GaAs, but is shown to be unstable at 450C. This paper reports the investigations carried out to understand the microstructure, nature of the interface and composition of sputter deposited and annealed (at different temperatures) Ni-Sb ohmic contacts on GaAs by TEM. Attempts were made to correlate the electrical properties of the films such as the sheet resistance and contact resistance, with the microstructure. The observations are corroborated by Scanning Auger Microprobe (SAM) investigations.

VERY LOW RESISTIVITY AuMn GATE OHMIC CONTACTS FOR GaInAs DIFFUSED JFETs

1988 ◽  
Vol 49 (C4) ◽  
pp. C4-453-C4-456 ◽  
Author(s):  
P. E. HALLALI ◽  
P. BLANCONNIER ◽  
L. BRICARD ◽  
J-C. RENAUD
Keyword(s):  
Ohmic Contacts ◽  
Low Resistivity

TEM Studies and Contact Resistance of Au/Ni/Ti/Ta/n-GaN Ohmic Contacts

2003 ◽  
Vol 764 ◽  
Author(s):  
D.N. Zakharov ◽  
Z. Liliental-Weber ◽  
A. Motayed ◽  
S.N. Mohammad
Keyword(s):  
Contact Resistance ◽  
Ohmic Contacts ◽  
High Resolution Electron Microscopy ◽  
X Ray ◽  
Electron Energy Loss Spectrometry ◽  
Resolution Electron ◽  
Order Of Magnitude ◽  
Contact Surfaces ◽  
Electron Energy Loss ◽  
Magnitude Difference

AbstractOhmic Ta/Ti/Ni/Au contacts to n-GaN have been studied using high resolution electron microscopy (HREM), energy dispersive X-ray spectrometry (EDX) and electron energy loss spectrometry (EELS). Two different samples were used: A - annealed at 7500C withcontact resistance 5×10-6 Ω cm2 and B-annealed at 7750C with contact resistance 6×10-5 Ω cm2. Both samples revealed extensive in- and out-diffusion between deposited layers with some consumption ofGaNlayerand formation of TixTa1-xN50 (0<x<25) at the GaN interface. Almost an order of magnitude difference in contact resistances can be attributed to structure and chemical bonding of Ti-O layers formed on the contact surfaces.

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