An Integrated a-IGZO UHF Energy Harvester for Passive RFID Tags (original) (raw)

2014, Ieee Transactions on Electron Devices

We present an ultrahigh frequency energy harvester based on low temperature processed a-IGZO (amorphous indium-gallium-zinc oxide) semiconductor on a glass substrate. The harvester is composed of a dipole antenna, matching network, and a double half-wave rectifier and is capable of delivering more than 1 V dc at a distance of 2 m from the transmitter antenna. In the proposed wireless system, this sensitivity corresponds to 2.75-m distance harvesting at 4-W (36 dBm) emitted power from a base station, which is within EPC regulations. The main element of the rectifier is the high-performance a-IGZO Schottky diode on glass, with a rectification ratio of 10 7 at ±1 V, a low threshold voltage of 0.6 V and a cutoff frequency of 3 GHz at 0 V bias. Index Terms-Amorphous indium-gallium-zinc oxide (a-IGZO), radio-frequency identification (RFID), Schottky diode, thin-film electronics, wireless power transmission. I. INTRODUCTION I TEM-level identification has been one of the main driven forces behind the research and development of circuitries based on semiconductors that can be deposited on neutral substrates like glass or plastic films. High-frequency (HF) operation (13.56 MHz) of diodes and integrated rectifiers based on organic semiconductors were already demonstrated [1]-[5]. However, until now no organic rectifier has been shown with a cutoff frequency higher than ∼400 MHz [3]. Although HF operation may be sufficient for many applications, ultimately ultra-HF (UHF) operation (868 MHz) will lead to a lower cost solution, as the antenna size and cost are smaller for UHF. Another important aspect in UHF harvesting applications is the communication range. As the path loss of an electromagnetic field in free space at far field is inversely proportional to the square of the distance, the threshold voltage of the diodes has to be as small as possible. In this respect, it should be noted that no integrated rectifiers based on organic nor oxide semiconductors have yet been reported that combine a high cutoff frequency and low threshold voltage, allowing UHF Manuscript