Electrophysical characteristics and structural parameters of metamorphic HEMT nanoheterostructures In 0.7 Al 0.3 As/In 0
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Electrophysical Characteristics and Structural Parameters of Metamorphic HEMT Nanoheterostructures In0.7Al0.3As/In0.7Ga0.3As/In0.7Al0.3As Containing Superlattices with Different Numbers of Periods in the Metamorphic Buffer G. B. Galieva, S. S. Pushkareva, A. S. Orekhovb, R. R. Galieva, E. A. Klimova, P. P. Maltseva, and R. M. Imamovb a
Institute of Ultrahigh Frequency Semiconductor Electronics, Russian Academy of Sciences, 117105, Moscow, Russia email: [email protected] b Shubnikov Institute of Crystallography, Russian Academy of Sciences, Leninskii pr. 59, Moscow, 119333 Russia email: [email protected] Received December 17, 2013
Abstract—The results of studying the electrophysical characteristics and structural parameters of metamor phic In0.7Al0.3As/In0.7Ga0.3As/In0.7Al0.3As HEMT nanoheterostructures epitaxially grown on GaAs (100) substrates have been presented. A linear metamorphic buffer with inserted unbalanced superlattices charac terized by different numbers of periods is used. Transmission electron microscopy has shown that an increase in the number of superlattice periods from 5 to 30 promotes the improvement of the crystal structure. In this case, the electrophysical parameters of metamorphic HEMT nanoheterostructures are also significantly improved. DOI: 10.1134/S1063774514030092
INTRODUCTION The metamorphic InAlAs/InGaAs/InAlAs high electronmobility transistor (HEMT) nanohetero structures on GaAs (100) substrates with a high In content are most promising for ultrahigh frequency electronics. Due to the greater technological effi ciency of GaAs substrates (as compared with InP sub strates), metamorphic HEMT (MHEMT) nanohet erostructures on GaAs substrates compete successfully with HEMT nanoheterostructures on InP substrates [1]. One of the main problems in the technology of MHEMT nanoheterostructures is to obtain high elec tron mobility in the quantum well. Defects (in partic ular, dislocations) formed as a result of the relaxation of elastic strains in the metamorphic buffer (MB) and intergrowth into the quantumwell region greatly affect electron mobility. Moreover, the surface of a grown MHEMTnanoheterostructure has a specific wavy crosshatch relief, which arises under the relax ation of the elastic strains accumulated in MB [2, 3]. The surface morphology, along with the electron mobility and twodimensional electron concentra tion, affect the properties and characteristics of micro wavefrequency devices based on such nanohetero structures. Therefore, the production of structurally perfect MHEMT nanoheterostructures on GaAs sub strates of a desired composition is an urgent problem. The structure and electrophysical characteristics of grown MHEMT nanoheterostructure are known to
depend strongly on both the technological growth conditions and the MB construction. The MB con struction is generally interpreted as a character of vari ation in the MB chemical composition in dependence of its thickness (linear or stepwise increase in the molar In portion with t
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