Direct intensity modulation and wireless data transmission characteristics of terahertz-oscillating resonant tunnelling diodes (RTDs) is reported. A direct intensity modulation of the RTD oscillators was demonstrated, and the frequency response was measured. It was found that the 3 dB cutoff modulation frequency was limited by the parasitic elements of the external circuit, and increased up to 4.5 GHz by reducing such parasitic elements. Wireless data transmission by direct amplitude shift keying was demonstrated using an RTD oscillating at 542 GHz with cutoff frequency of 1.1 GHz. The BERs for bit rates of 2 and 3 Gbit/s were found to be 2 × 10 28 and 3 × 10 25 , respectively.Introduction: High-capacity short-distance wireless communication is an important application of the terahertz (THz) range [1, 2]. Thus, compact and coherent solid-state THz sources that can be modulated directly are highly desirable. A good candidate for THz sources is the resonant tunnelling diode (RTD), which can oscillate in the THz range at room temperature [3][4][5][6]. We have reported RTDs with fundamental oscillation of 1.04 THz [4] and high output power ( 400 mW) oscillation at around 550 GHz [5]. The modulation of the output of THz sources is important for communication. In this Letter, we demonstrate a direct modulation of the output power of an RTD oscillator and measure its frequency response. In addition, we also demonstrate wireless data transmission by a direct amplitude shift keying (ASK) of the RTD.

We report resonant tunneling diode (RTD) oscillators with a high output power of around 400 µW at frequencies of 530–590 GHz. RTDs with a graded emitter and thin barriers were employed to obtain large negative differential conductance at high frequencies for high output power. An optimized structure of offset slot antennas was also used to maximize the radiation conductance. The highest output power obtained in this study was 420 µW at 548 GHz for an RTD with a peak current density of 24 mA/µm2; the RTD was placed 58 µm apart from the center of a 130-µm-long slot antenna.

The effects of Pr 3þ substitution on electrical properties of Bi(Fe 0:95 Mn 0:05 )O 3 (BFMO) thin films are investigated. The leakage current densities of BFMO films can be significantly suppressed by Pr 3þ substitution. Dielectric analysis reveals that dielectric constants of the films increase with increasing Pr 3þ content. Reduced loss tangents are obtained in Pr 3þ -substituted BFMO films. Ferroelectric measurements demonstrate that Pr 3þ substitution is helpful for lowering the coercive fields of films. In addition, a double hysteresis loop is observed in the BFMO film with 25% Bi 3þ substituted by Pr 3þ . This may be ascribed to the existence of the defect-complexes. #

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