Electronics and sensors based on pyroelectric AlGaN/GaN heterostructures

Abstract

Electronic transport in semiconductors that possess high internal spontaneous and piezoelectric polarization opens up a new field of pyroelectronics and pyrosensors. The pyroelectric character of group-III-nitrides with wurtzite crystal structure yields a novel degree of freedom in designing and tailoring devices for modern micro- and nanoelectronic applications. Furthermore, spontaneous and piezoelectric polarization induced surface and interface charges can be used to develop very sensitive but robust sensors for the detection of ions, gases and polar liquids. We present a review of both theoretical and experimental studies of spontaneous and piezoelectric polarization present in AlGaN/GaN heterostructures as well as the electronic transport properties of polarization induced two-dimensional electron gases which are formed at the AlGaN/GaN interface due to the difference in the total polarization of two adjacent III-nitride layers. We demonstrate that the two-dimensional electron gases (2DEGs) achieved without modulation doping are very suitable as channel of high electron mobility transistors optimally suited for high power and high frequency applications (PART A) as well as for various kinds of sensors which can be operated in harsh environments (PART B)

Effects of interface states and temperature on the C-V behavior of metal/insulator/AlGaN/GaN heterostructure capacitors

“…The supposed band offset at the AlGaN/GaN interface was 70% of the bandgap discontinuity. 43,44 The estimated influence of temperature on the band offset and the spontaneous and piezoelectric polarization at the Al 0.25 Ga 0.75 N / GaN interface 36,41,43,[45][46][47][48][49] is negligible in the first approximation. Quantum corrections to the C-V curves are also unnecessary in the studied case.…”

“…The piezoelectric polarization due to biaxial strain at the AlGaN/GaN interface is expressed by the following formula: 36 P pe ͑AlGaN/GaN͒ = P pe ͑AlGaN͒ − P pe ͑GaN͒ = 2ͩ a GaN a AlGaN − 1ͪͩe 31 − e 33 C 13…”

Development of 2" AlN Substrates Using SiC Seeds

“…to get the desired properties of the heterostructure, for example, to achieve two-dimensional electron gas without modulation doping (Ambacher et al, 2003). Note that an "effective" cost of single crystal bulk AlN substrates could be rather low if repeated use (removal of the AlN substrate by laser-lift off and recycling 9 ) is realized.…”

Remote sensing system for hydrogen using GaN Schottky diodes

“…Simple Schottky diode or field-effect transistor structures fabricated in GaN (and SiC [15]) are sensitive to a number of gases, including hydrogen and hydrocarbons [1,7,24,25]. Gas sensors based on GaN could be integrated with high-temperature electronic devices on the same chip [26,27].…”