Strain–Stress Analysis of AlGaN/GaN Heterostructures With and Without an AlN Buffer and Interlayer

Abstract

The strain-stress analysis of Al x Ga 1)x N/GaN (x = 0.3) heterostructures with and without a high-temperature HT-AlN interlayer (IL) grown on sapphire (Al 2 O 3 ) substrates and AlN buffer/Al 2 O 3 templates via metal organic chemical vapour deposition (MOCVD) was carried out based on the precise measurement of the lattice parameters by using high-resolution X-ray diffraction (HRXRD). The a-and c-lattice parameters were measured from the peak positions that were obtained by rocking the theta axis at the vicinity of the symmetric and asymmetric plane reflection angles, followed by the in-plane and out-of-plane strains. Then, the biaxial and hydrostatic components were extracted from the total strain values that were obtained and were then discussed in the present study as the effect of the HT-AlN buffer and IL. The AlN buffer layer (BL) affects the strain values of the AlGaN ternary layer (TL). A further effect was realized by inserting an AlN IL between GaN BL and AlGaN TL. However, the experimental results also show that an AlN IL changes the strain behaviour in the a-and c-directions of the AlGaN TL from the tensile to compressive and the compressive to tensile type, respectively. These similar behaviours were observed in hydrostatic strain, biaxial strain and stress. Their reasons are explained with an effective a-lattice parameter, post-growth cooling and lattice and thermal mismatches. PACS: 61.05.cp, 68.55,ag, 81.15.Gh, 78.55.Cr KEY WORDS: high electron mobility transistors, high-resolution X-ray diffraction, metal organic chemical vapour deposition, strain Ó

Investigation of structural, optical and morphological properties of InGaN/GaN structure

“…All kind of dislocations are dependent on lateral mosaic length, tilt and twist angles. As reported by Metzger et al [12], GaN films in (002) average twist angle is related with edge Burgers vector [b = 1/3 (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)] type dislocation density. Also average tilt angle, is related with monotonous Burgers vector b = (0001) screw type dislocation [11].…”

“…For S.B there is no considerable difference in tilt angle values with increasing temperature. The situation is the same for S.C. Lateral crystal length values for GaN [14,15]. In Fig.…”

“…Dislocations between 10 8 and 10 12 cm −2 are accepted as threadening dislocations (TD) and nitride-based layers deposited on sapphire, silicon carbide, and silicon wafers which has lattice mismatch show threadening dislocation behaviour [15,16].…”

Plasma assisted molecular beam epitaxy growth and effect of varying buffer thickness on the formation of ultra-thin In0.17Al0.83N/GaN heterostructure on Si(111)

“…It is followed by in-plane and out-of plane strain component evaluation. 25 Strain in c-direction of GaN layer reveals compressive behavior in the order of 10 À4 , whereas tensile behavior in the order of 10 À3 is seen in a-direction of GaN layer. With decreasing buffer thickness the compressive and tensile strain in c-and a-direction increases, resulting degraded GaN quality.…”

Determination of Temperature-Dependent Stress State in Thin AlGaN Layer of AlGaN/GaN HEMT Heterostructures by Near-Resonant Raman Scattering

“…In previous reports, the strain or stress in the AlGaN layer of AlGaN/GaN heterostructures was characterized typically by using X-ray diffraction [12,13]. However, the reflection peaks of some asymmetric planes in AlGaN barrier layer are always invisible due to the thin thickness and poor interference of the plane [12]. So, the in-plane lattice constant and the biaxial strain of AlGaN layer cannot be measured directly using this method.…”