Possible realization of near optimum efficiency from n-Si-Ge/p-Ge-Si DDR Hetero Structure IMPATT Diode

Abstract

A p-n junction under reverse bias avalanche breakdown condition is capable of producing high frequency rf power in Impatt mode. With the advancement of Device Technology, the present state of art reports realization of alloy Si-Ge junction, Si-Ge hetero junction. Introduction of a n-Ge and p-Ge impurity bumps near the junction face on respective side of Si p-n junction leaves an asymmetrical hetero structure junction which has become the scope of study of this paper for operation at 15 and 96 GHz. Three tier sophisticated computer algorithm has been framed and used for Impatt analysis of resulting n-Si-Ge/p-Ge-Si Hetero Structure reveals realization of device efficiency as high as 29.6% (Theoretical Optimum Efficiency of Impatt Diode=31%) and also high value of negative conductance. Presence of Ge layer near junction and an order high carrier ionization rate in Ge compared to Si localizes the avalanche zone, which pushes the efficiency and RF power generation. Similar results are also noticed for 96 GHz operations. The performance from this structure is observed to be superior by considerable extent as compared to Si and Ge homo structure. However the complementary hetero structure having the form n-Ge-Si/p-Si-Ge is observed to exhibit performance almost on par to Si and Ge homo structures. The results are highly encouraging which may make Si-Ge Hetero Structure Diode as a microwave generator.