[Paper Review] Comprehensive structural and optical analysis of differently oriented Yb-implanted $β$-Ga$_2$O$_3$

Joanna Matulewicz, R. Ratajczak+10 more|arXiv (Cornell University)|Mar 10, 2026

Ga2O3 and related materials0 citations

TL;DR

This study investigates how Yb implantation affects the structure and optical response of β-Ga2O3 across three crystal orientations (001, 010, -201), using HRXRD, RBS/c, Raman, PL, and Monte Carlo simulations to correlate defects with Yb luminescence.

ABSTRACT

This study presents investigations of Yb-doped $β$-Ga$_2$O$_3$, an ultrawide bandgap semiconductor with potential use in future power and optoelectronic devices operating in high-radiation environments. The research has focused on the problem of structural damage caused by the implantation of Yb-ions into three differently oriented crystals and the optical response of created systems. The (001), (010), and (-201)-oriented $β$-Ga$_2$O$_3$ crystals were implanted with three different fluences of 150 keV Yb ions and examined using a variety of experimental techniques: high-resolution X-ray diffraction (HRXRD), Rutherford backscattering spectrometry in channeling mode (RBS/c), Raman and photoluminescence (PL) spectroscopies, to provide comprehensive information about studied systems. Furthermore, the RBS/c studies were supported by Monte Carlo simulations. The results show distinctions between differently oriented crystals. In particular, (010)-oriented crystals are characterized by the lowest concentration of extended defects and the presence of compressive stress. In contrast, samples with the other two orientations exhibit tensile stress and significantly higher levels of extended defects. Interestingly, the PL spectra of (010)-oriented $β$-Ga$_2$O$_3$ show the lowest emission from Yb$^{3+}$ ions, suggesting that specific types of extended defects, whose formation is more favorable in the other two orientations than in (010), enhance Yb$^{3+}$ luminescence instead of suppressing it.

Motivation & Objective

• Understand how Yb implantation damages β-Ga2O3 in three crystallographic orientations (001, 010, -201).
• Correlate defect structures with optical responses, especially Yb3+ luminescence, after annealing.
• Quantify strain, phase transformations, and defect types using complementary techniques and simulations.
• Evaluate how implant dose ( fluences: 1e15, 1e14, 1e13 ions/cm2) influences structural and optical properties.

Proposed method

• Ion implant β-Ga2O3 with 150 keV Yb ions at fluences of 1e15, 1e14, 1e13 ions/cm2; tilt ~7° to avoid channeling; room temperature.
• Anneal in oxygen at 800°C for 10 minutes using a rapid thermal annealer.
• Characterize with high-resolution X-ray diffraction (HRXRD) to assess crystalline quality and strain.
• Perform Rutherford backscattering spectrometry in channeling mode (RBS/c) to analyze defect distributions and dopant profiles.
• Use Monte Carlo simulations with McChasy to interpret RBS/c results and distinguish simple (RDA) and extended (DIS) defects.
• Supplement with Raman spectroscopy to probe phonon modes and lattice dynamics, and photoluminescence (PL) to study Yb3+ emission and defect-related bands.

Figure 1 : The unit cell of $\beta$ -Ga 2 O 3 created by VESTA [ 22 ] .

Experimental results

Research questions

• RQ1 How does implantation orientation (001, 010, -201) influence defect formation and strain in Yb-implanted β-Ga2O3?
• RQ2 What is the relationship between radiation-induced phase transformations (β to γ, and amorphization) and implant fluence across orientations?
• RQ3 How does Yb3+ luminescence depend on crystallographic orientation and defect landscape after annealing?
• RQ4 Can Monte Carlo channeling simulations (McChasy) explain orientation-dependent defect distributions observed by RBS/c?
• RQ5 What is the role of extended defects, such as bending channel defects, in enhancing or quenching Yb-related luminescence?

Key findings

• (010)-oriented crystals exhibit the lowest concentration of extended defects and compressive strain after Yb implantation.
• (001) and (-201)-oriented crystals develop tensile strain and show higher levels of extended defects compared to (010).
• γ-Ga2O3 phase forms in implanted zones at certain fluences, with complete γ phase evident at 1e14 ions/cm2 and partial persistence at 1e15 ions/cm2; annealing reduces γ phase in some cases.
• At the highest fluence (1e15 ions/cm2), partial amorphization begins, and lattice quality deteriorates in certain orientations; annealing can alter these trends by promoting partial recrystallization.
• PL shows a strong Yb3+ emission (980 nm) and a broad native defect-related band (3.8–2 eV) whose intensity correlates inversely with defect excitation; (001) and (-201) show higher Yb3+ luminescence than (010).
• RBS/c analysis, supported by McChasy simulations, indicates similar simple defect (RDA) distributions across orientations, but lower dechanneling (DIS) in (010) due to fewer bending-channel defects.
• Results suggest dislocations or bending-channel defects may act as Yb3+ luminescence enhancers by trapping dopants or stabilizing energy transfer.

Figure 2 : HRXRD 2 $\theta$ scans of (-201)-oriented $\beta$ -Ga 2 O 3 crystal (a) implanted with Yb ions with different fluences and (b) implanted with Yb with fluence of $1\cdot 10^{15}$ ions/cm 2 and annealed in oxygen at 800°C for 10 minutes.