X-ray diffraction and Raman characterization of β-Ga2O3 single crystal grown by edge-defined film-fed growth method

Abstract

The crystallinity and wafer uniformity of (2¯01) and (010) oriented β-Ga2O3 substrates grown by edge-defined film-fed growth (EFG) were investigated by laboratory X-ray diffraction (XRD), synchrotron XRD, polarized Raman spectroscopy, and Raman mapping. XRD results indicated that the EFG substrates had superior crystallinity and high uniformity. Position-dependent XRD ω-rocking curves recorded across a 50.8-mm-diameter substrate had small standard deviations of δF = 1.6% for the full width at half maximum and δP = 2.8% for the peak intensity. The radius of curvature was measured to be 37.7 m for the (2¯01) substrate and 16.4 m for the (010) substrate. The results of synchrotron XRD with various beam sizes suggested that the curving of crystal planes was mainly along the [010] growth direction rather than along the [102] direction. Raman spectra showed that Sn doping up to 3.3 × 1018 cm−3 did not give rise to a notable Raman peak shift. The strain distribution evaluated by Raman mapping implied the high uniformity of both (2¯01) and (010) substrates. From these results, it was concluded that β-Ga2O3 ingots grown by EFG have high crystallinity and can be treated as three-dimensionally uniform bulk crystals in the cases of both undoped and Sn-doped growth.

Raman Spectroscopic Characterization of Chemical Bonding and Phase Segregation in Tin (Sn)-Incorporated Ga2O3

“…But, there is a nominal peak shift observed in such Raman active vibration modes. Yao et al have reported similar findings, which is due to the localized deformation at octahedral Ga II 3+ sites than long-range bond stretching. On the contrary, asymmetric tailoring of the Raman active vibrational peaks at a higher frequency range starts appearing from x ≥ 0.2, where the interstitial accumulation of the SnO 2 phase begins overtaking the Sn incorporation process.…”

“…Additionally, there are several reports in the recent literature suggesting the same theoretical prediction. 52 , 53 Moreover, decreasing peak intensity, related to the mid-frequency range (320, 346, and 415 cm –1 ), with increasing Sn concentration confirms selective Sn incorporation at Ga II 3+ sites. But, there is a nominal peak shift observed in such Raman active vibration modes.…”

High Performance β‐Ga2O3 Schottky Barrier Transistors with Large Work Function TMD Gate of NbS2 and TaS2

“…[31][32][33][34][35] Likewise, pure vdW junction between metallic TMDs and β-Ga 2 O 3 seems unlikely in the present study. Figure 1b [36][37][38] Atomic force microscopy (AFM) to measure thickness of Nb(Ta)S 2 and β-Ga 2 O 3 has been conducted with MESFET structure, and exemplary 3D thickness profiles are thus shown in Figure 1c,d in literature (qΦ W of NbS 2 , [39,40] TaS 2 , [39,41] and β-Ga 2 O 3 [2,3] ≈6.0, ≈5.6, and ≈4.1 eV, respectively). Such difference is attributed to possible existence of ultrathin oxide (NbO x or TaO x ) on TaS 2 or NbS 2 , since those TMDs are so weak to oxidation in air ambient.…”

Growth and characterization of the β-Ga2O3 (011) plane without line-shaped defects

“…While the Au and Bu modes are infrared active, 30 A g and B g are Raman active. Different factors lead to various Raman peaks.…”