TU36-(2)-5
Enhancing light-emission efficiency from
SLMOS
tunneling diodes
by
KOH
wet etching
"Wu-Ping Huang, "3bChing-Fuh
Lin
"Graduate Institute of Electro-Optical Engineering, National Taiwan University, Taipei,
Taiwan,
R.O.C,
balsa
with Graduate Institute
of Electronics Engineering.,
and
Dept. of
Electrical Engineering
Phone: 886-2-2363525 1 ext 339, Fax: 886-2-23677467, Email: [email protected]
Abstract - It is confirmed that the efficient light emits ut the Si bandgap energv in the MOS tunneling diode structure. But its external quantum efficiency only about -10" . We make the surface roughness in the Anisotropic Dissolution of Si(100) in Aqueous KOH. Suck surfoce roughness enkancepkononassisted radiative recombination. By KOH etching, the external quantum eficiency arrived at -10'.Introduction
Here we report that by use of Si@ nanoparticles in the oxide layer in metal-oxide-silicon (MOS) structure and anisotropic wet etching solution KOH to improve the surface quality, the extemal quantum efficiency of electroluminescence (EL) at the Si bandgap energy could be enhanced to 1.5x1(r4.
Experiment data demonstration
The processing steps were as follows: First the native oxide upon the silicon wafer was removed. We use KOH solution to improve the surface quality of silicon. Then the solution with Si@ nanoparticles was spun onto the wafer and dried in an oven. Nanoparticles are with a feature size of 8-1 1 nm. The thichess of this nanoparticle layer is about 150 m. A thick layer of AI was evaporated onto the backside of the silicon wafer to form the electrical contact. Finally, the Ag paint was directly applied on top of the nanoparticles to hold a Au wire for another electrical contact. A schematic of the device is shown in Fig.1. Fig1 also shows a scanning-electron microscope photo of the cross-sectional view of the device.
-
Fig. I Schematic'of MOS tunneling diode with nanoparticlcs and SEM photo ofcross-
sectional view.
Fig. 2 Output power & extcmal quanNm effciency
YS. injection cumnt
Fig. 2 shows the perfomance of this device. The EL extemal quantum efficiency rapidly increases and reaches 1.5~10~' for operation current between 20 to 30 mA, then slightly drops to lo'* due to the thermal effect. The EL power could be 10
pW
at the injection current of 100 mA(current density 12.7 Ncm'). The power is measured only from the periphery of the Ag paint pad. Because this pad could obstruct a portion of light generated from the devices, the actual light power might be more than 10 pW. If the total EL power is included, the EL quantum efficiency probably exceeds IO5.We have demonstrated that the use of S i Q nanoparticles and KOH wet etching could make the highly efficient Si-MOS tunneling diode. The possibility of efficient EL from MOS tunneling diodes gives the great promise of optical interconnect among ULSI chiops based fully on the CMOS technology.
Conclusions
0-7803-7766-4/03/$l7.00 82003 IEEE
