Title :
Characteristics of Al0.4Ga0.6N/GaN heterostructure varactor diodes
Author :
Mutamba, K. ; Saglam, M. ; Sydlo, C. ; Hartnagel, Hans L. ; Megej, A. ; Daumiller, I.
Author_Institution :
Inst. fuer Hochfrequenztechnik, Technische Univ. Darmstadt, Germany
Abstract :
This paper reports on the electrical characteristics of MOCVD-grown AlxGa1-xN /GaN (x=0.4) heterostructure barrier varactors. The influence of strong piezoelectric and spontaneous polarisation effects is highlighted by the asymmetric behaviour of the capacitance-voltage characteristics of the fabricated devices. The obtained capacitance modulation values of 1.4 and 1.1 for negative and positive bias, respectively, show that appropriate bandgap engineering is needed in order to take advantage of the offered higher barrier heights of nitride-based heterostructures. A theoretical analysis including polarisation charges at layer interfaces and the resulting effects on the device energy band-diagram supports the obtained results.
Keywords :
III-V semiconductors; MOCVD; aluminium compounds; energy gap; gallium compounds; varactors; Al0.4Ga0.6N; GaN; MOCVD-grown varactors; asymmetric behaviour; bandgap engineering; capacitance modulation; capacitance-voltage characteristics; electrical characteristics; energy band-diagram; frequency multiplier; heterostructure barrier varactors; heterostructure varactor diodes; higher barrier heights; layer interfaces; nitride-based heterostructures; piezoelectric polarisation; polarisation charges; polarisation effects; theoretical analysis; Capacitance; Capacitance-voltage characteristics; Diodes; Frequency; Gallium arsenide; Gallium nitride; Indium compounds; Indium gallium arsenide; Piezoelectric polarization; Varactors;
Conference_Titel :
Semiconductor Conference, 2004. CAS 2004 Proceedings. 2004 International
Print_ISBN :
0-7803-8499-7
DOI :
10.1109/SMICND.2004.1402828
