Intrinsic degradation mechanism of nearly lattice-matched InAlN layers grown on GaN substrates
نویسندگان
چکیده
Thanks toits high refractive index contrast, band gap and polarization mismatch compared to GaN, In0.17Al0.83N layers lattice-matched to GaN are an attractive solution for applications such as distributed Bragg reflectors, ultraviolet light-emitting diodes, orhigh electron mobility transistors. In order to study the structural degradation mechanism of InAlN layers with increasing thickness, we performed metalorganic vapor phase epitaxy of InAlN layers of thicknesses ranging from 2 to 500 nm, on free-standing (0001) GaN substrates with a low density of threading dislocations, for In compositions of 13.5% (layers under tensile strain), and 19.7%(layers under compressive strain). In both cases, a surface morphology with hillocks isinitially observed, followed by the appearance of V-defects. We propose that those hillocks arise due to kinetic roughening, and that V-defects subsequently appear beyonda critical hillock size. It is seen that the critical thickness for the appearance of V-defects increases together with the surface diffusion length either by increasing the temperature or the In flux because of asurfactant effect.In thick InAlN layers, a better (worse) In incorporation occurring on the concave (convex) shape surfaces of the V-defects is observed leading to a top phase-separated InAlN layer lying on the initial homogeneous InAlN layerafterV-defects coalescence.It is suggested that similar mechanisms could be responsible for the degradation of thick InGaN layers.
منابع مشابه
Effect of lattice mismatch on gate lag in high quality InAlN/AlN/GaN HFET structures
Grown lattice matched to GaN, InAlN-based heterojunction field effect transistors (HFETs) are promising due to the relatively large band discontinuity at the interface and lack of misfit strain. Despite the recent progress in the growth, there still exists some questions as to the true lattice matching condition of InAlN to GaN due to discrepancies in the value of the lattice parameters of the ...
متن کاملGrowth and characterization of lattice-matched InAlN/GaN Bragg reflectors grown by plasma-assisted molecular beam epitaxy
متن کامل
Status of the Emerging InAlN/GaN Power HEMT Technology
The InAlN/GaN heterojunction appears to be a new alternative to the common AlGaN/GaN configuration with higher sheet charge density and higher thermal stability, promising very high power and temperature performance as well as robustness. This new system opens up the possibility to scale the barrier down to 5 nm while maintaining nearly its ideal materials and device properties. The status, foc...
متن کاملOptoelectronic properties of InAlN/GaN distributed bragg reflector heterostructure examined by valence electron energy loss spectroscopy.
High-resolution monochromated electron energy loss spectroscopy (EELS) at subnanometric spatial resolution and <200 meV energy resolution has been used to assess the valence band properties of a distributed Bragg reflector multilayer heterostructure composed of InAlN lattice matched to GaN. This work thoroughly presents the collection of methods and computational tools put together for this tas...
متن کاملHot electron induced non-saturation current behavior at high electric field in InAlN/GaN heterostructures with ultrathin barrier
The high-field transport characteristics of nearly lattice-matched InAlN/GaN heterostructures with different barrier thickness were investigated. It is found that the current in the InAlN/GaN heterostructures with ultrathin barrier shows unsaturated behaviors (or secondary rising) at high voltage, which is different from that of AlGaN/GaN heterostructures. This phenomenon is more obvious if the...
متن کامل