Title :
Modification of GaAs Schottky barriers using a-Si:H interfacial layers
Author :
Sambell, A.J. ; Wood, John
Author_Institution :
Dept. of Electr. Eng., York Univ., UK
Abstract :
The electrical characteristics of metal/a-Si:H/n-GaAs diode structures were studied in order to investigate the role of the a-Si:H and the claim of no barrier at the GaAs/a-Si:H interface. Diodes were fabricated using a-Si:H layers between 30 and 1920 AA thick, with Al and Mg metallization, and the current-voltage and capacitance-voltage characteristics were examined. Rectifying Schottky barriers were formed at Al/a-Si:H junctions, while good ohmic contacts were formed at Mg/a-Si:H junctions, enabling effects due to the metal/a-Si:H and a-Si:H/GaAs interface to be isolated. A dramatic increase in the forward turn-on voltage was observed as the thickness of the a-Si:H layer increased. The diode behavior can be explained by considering three effects in series: (1) an a-Si:H/GaAs barrier of about 0.6 eV, consistent with Fermi-level pinning in GaAs; (2) a metal/a-Si:H barrier, dependent on the metallization; and (3) space-charge-limited current (SCLC) in the bulk a-Si:H. The SCLC effectively gives rise to a voltage-dependent resistance and causes the increased turn-on voltages.<>
Keywords :
III-V semiconductors; Schottky-barrier diodes; aluminium; gallium arsenide; magnesium; semiconductor junctions; semiconductor-metal boundaries; silicon; 30 to 1920 A; Al-Si:H-GaAs; Fermi-level pinning; Mg-Si:H-GaAs; Schottky barriers; amorphous Si:H; capacitance-voltage characteristics; diode behavior; electrical characteristics; forward turn-on voltage; ohmic contacts; semiconductors; space-charge-limited current; voltage-dependent resistance; Gallium arsenide; Interface states; Logic circuits; Plasma applications; Plasma chemistry; Plasma temperature; Schottky barriers; Schottky diodes; Silicon; Voltage;
Journal_Title :
Electron Device Letters, IEEE
