Impact of Group-II Acceptors on the Electrical and Optical Properties of GaN

A point defect in acceptor-doped bulk free standing GaN grown by the high nitrogen pressure solution method (HNPS) was investigated using electron paramagnetic resonance (EPR) spectroscopy. A nearly isotropic spectrum with g-value of 1.984 is observed after illumination with 2.8 eV light and is stable after removal of the light. Comparison with earlier work on p-type GaN films and SIMS data on the HNPS substrates suggests that the defect is related to an acceptor, heavily compensated during growth by oxygen. Time-dependent photo-EPR data are well modeled as a single defect-to-band transition where the defect level is 0.67 eV above the valence band edge. Although Mg-and Be-doped samples were studied, only those samples containing Be produced the EPR signal. This observation, coupled with the similarity of the defect level measured to that predicted from the theory of others, suggests that the defect is related to a Be impurity.

“…4 are consistent with those predicted for the acceptor level of Be [15]. Furthermore, the steady-state photo-EPR results for the purely Be-doped sample S4 (Fig.…”

Section: à3supporting

confidence: 88%

Determination of an acceptor level in bulk GaN grown by high nitrogen pressure solution method

Dashdorj

Zvanut

Boćkowski

2015

“…In Refs. it was found that Be

_{Ga}

also leads to hole localization onto a nearest‐neighbor nitrogen atom. Unlike for Mg

_{Ga}

, hole localization at Be

_{Ga}

gives rise to a much larger ionization energy (calculated to be 450 meV in Ref.…”

Section: Acceptor Impurities In Ganmentioning

confidence: 99%

“…Another alternative acceptor in GaN is Zn, which was used in early light‐emitting diodes to generate sub‐band‐gap luminescence (). Like Mg

_{Ga}

and Be

_{Ga}

, Zn

_{Ga}

has been found to lead to hole localization . Using the

normalLDA + U

‐based approach, it was found that Zn

_{Ga}

has an ionization energy of 0.32 eV (), while hybrid functional calculations gave an ionization energy of 0.46 eV ().…”

Section: Acceptor Impurities In Ganmentioning

confidence: 99%

“…Like Mg

_{Ga}

and Be

_{Ga}

, Zn

_{Ga}

has been found to lead to hole localization . Using the

normalLDA + U

‐based approach, it was found that Zn

_{Ga}

has an ionization energy of 0.32 eV (), while hybrid functional calculations gave an ionization energy of 0.46 eV (). A mechanism for blue luminescence in Zn‐doped GaN has been proposed (), associating a luminescence peak at 2.94 eV with an electron recombining into a Zn

_{Ga}

‐related gap state.…”

Section: Acceptor Impurities In Ganmentioning

confidence: 99%

See 1 more Smart Citation

First‐principles theory of acceptors in nitride semiconductors

Lyons

Alkauskas

Janotti

et al. 2015

Self Cite

127

107

Acceptor defects and impurities play a critical role in the performance of GaN-based devices. Mg is the only acceptor impurity that gives rise to p-type conductivity, while other acceptors (such as C N impurities and V Ga defects) act as sources of compensation and trapping. From the point of view of theory, understanding the physics of acceptor species in GaN has long been a challenge. In the past, limitations of computational techniques made it difficult to quantitatively predict crucial quantities such as thermodynamic and optical transition levels. However, advances in first-principles calculations, including the use of hybrid functionals in density functional theory, have led to a resurgence in efforts to understand properties of acceptors in nitrides. After briefly discussing advances in theoretical techniques, we review recent computational work on acceptor impurities in GaN and compare theoretical results with the available experimental data. We also present new hybrid density functional calculations on the transition levels of V Ga and its complexes with O and H impurities. The results indicate that donor impurities significantly lower V Ga transition levels, and that V Ga -3H and V Ga -O N -2H complexes give rise to yellow luminescence. We also discuss the properties of acceptor impurities in AlN and InN.

“…Despite theoretical studies showing that Be at a Ga site (

{Be}_{Ga}

) is a shallow acceptor, only slight p‐type conductivity was observed in GaN . The reason for this is that

{Be}_{Ga}

is a deep acceptor (

E_{normalV} + 0.55 eV

) . Nevertheless, Be is now considered for white light–emitting diodes (LEDs) or for achieving high‐resistivity GaN layers .…”

Section: Introductionmentioning

confidence: 99%

Minority Carrier Traps in Ion‐Implanted n‐Type Homoepitaxial GaN

Alfieri

Sundaramoorthy

2019

Ion implantation is a key step for device processing. This is required for anode/cathode or junction termination extension formation, which relies on the use of multiple‐energy implantation profiles (box profile). However, electrically active defects are known to arise after implantation, especially in the implant‐tail region. Although there are studies on majority carrier traps in implanted GaN, not much is known on minority carrier traps. For this reason, the electrical characterization of minority carrier levels is conducted in ion‐implanted n‐type GaN. Three electrically active levels are found in the 0.18–1.2 eV energy range, above the valence band edge, and their nature is discussed in the light of theoretical studies found in the literature.