ABSTRACT
Tunnel Diodes are semiconductor devices with a unique property: Negative Differential Resistance (NDR). A lot of research has focused on the properties and applications of tunnel diodes since their first introduction by Esaki in 1958 [1]. Advances in semiconductor technology, particularly Molecular Beam Epitaxy, has led to the introduction of various types of tunnel diodes in a variety of material systems [2,3]. The most popular tunnel diodes have been the intra-band Resonant Tunneling Diodes (RTD) [4,5]. RTD’s have higher current densities and lower capacitance compared to the Esaki type of diodes. Hence RTD’s are favourite candidates for applications such as high frequency (up to THz) oscillators [4,6] and digital logic [7,8]. The inter-band tunnelling diodes (Esaki and modified Esaki diodes) also have some distinct advantages. They exhibit high peak to valley current ratios (PVCR) [9, 10] and have wide peak to valley voltage spans useful for MMIC applications [11]. It is however a challenge to improve the peak current density and frequency of operation of the inter-band diodes so that their potential for MMIC applications is realised [12].
