Da-Jin Kim

Optimization of the intrinsic length of a PIN diode for a reconfigurable antenna

Through the characterization of a fabricated PIN diode with the aid of a simulation, a structural guideline for a reconfigurable antenna is developed. By comparing the conductivity with the equivalently normalized power, an optimal intrinsic channel length is determined. Simulation data show that a high carrier concentration is sustained along both the vertical and lateral directions in the intrinsic region. Due to the simple fabrication process and the controllability of the exposed channel region as well as the high carrier concentration with good uniformity, the proposed PIN diode is a viable candidate for a future antenna.

Reconfigurable Yagi-Uda antenna based on a silicon reflector with a solid-state plasma

This paper describes the fabrication and characterization of a reconfigurable Yagi-Uda antenna based on a silicon reflector with a solid-state plasma. The silicon reflector, composed of serially connected p-i-n diodes, forms a highly dense solid-state plasma by injecting electrons and holes into the intrinsic region. When this plasma silicon reflector is turned on, the front-realized gain of the antenna increases by more than 2 dBi beyond 5.3 GHz. To achieve the large gain increment, the structure of the antenna is carefully designed with the aid of semiconductor device simulation and antenna simulation. By using an aluminum nitride (AlN) substrate with high thermal conductivity, self-heating effects from the high forward current in the p-i-n diode are efficiently suppressed. By comparing the antenna simulation data and the measurement data, we estimated the conductivity of the plasma silicon reflector in the on-state to be between 104 and 105 S/m. With these figures, silicon material with its technology is an attractive tunable material for a reconfigurable antenna, which has attracted substantial interest from many areas, such as internet of things (IoT) applications, wireless network security, cognitive radio, and mobile and satellite communications as well as from multiple-input-multiple-output (MIMO) systems.

On-Chip Curing by Microwave for Long Term Usage of Electronic Devices in Harsh Environments

Microwave-induced thermal curing is demonstrated to improve the reliability and to prolong the lifetime of chips containing nanoscale electron devices. A film containing graphite powder with high microwave absorbing efficiency was fabricated at low cost. The film is flexible, bendable, foldable, and attachable to a chip. A commercial off-the-shelf chip and a representative 3-dimensional (3D) metal-oxide-semiconductor field-effect transistor (MOSFET), known as FinFET, were utilized to verify the curing behaviors of the microwave-induced heat treatment. The heat effectively cured not only total ionizing dose (TID) damage from the external environment, but also internal electrical stress such as hot-carrier injection (HCI), which are representative sources of damages in MOSFET insulators. Then, the characteristics of the pre- and post-curing electron devices are investigated using electrical measurements and numerical simulations.

A frequency reconfigurable dipole antenna with solid-state plasma in silicon

A frequency reconfigurable dipole antenna based on a silicon radiator is presented. The silicon radiator is activated with the aid of highly dense solid-state plasma by injecting carriers into the intrinsic region of p-i-n diodes. The fabrication and design guideline of the reconfigurable dipole antenna with this plasma radiator are described. When the plasma radiator is activated or deactivated, the length of the dipole arm changes, which means that the operating frequency of the dipole antenna is reconfigurable. When all the channels in the plasma radiator are activated, the operating frequency is tuned from 6.3 GHz to 4.9 GHz. The measured tunable bandwidth of our fabricated dipole antenna is approximately 31%, which is a practical value in comparison to conventional frequency reconfigurable antennas whose tunable bandwidth is in a range from 20% to 50%. To further support the validity of our results, we provide the well-matched simulation results from an antenna simulation. These results demonstrate that silicon with its commercial technology, which has not attracted attention in comparison to a metal antennas, is a promising tunable material for a frequency reconfigurable antenna. This plasma-based reconfigurable antenna has great potential for use in the dynamic communication environment.