Γ7valence band symmetry related hole fine splitting of bound excitons in ZnO observed in magneto-optical studies

Abstract

The symmetry ordering of the valence bands in ZnO is derived from high-resolution magneto-optical measurements of bound excitons. We report on the experimental observation of a hole state related fine splitting for bound excitons in the Voigt configuration. This splitting is related to a nonzero Landé g value g Ќ for hole states from the A valence band. Based on theoretical considerations, the symmetry of the uppermost valence band is doubtlessly identified as ⌫ 7 . This attribution is confirmed by polarization and angular resolved magnetophotoluminescence spectroscopy.

Donor bound excitons involving a hole from the B valence band in ZnO: Time resolved and magneto-photoluminescence studies

“…1(c)). This prediction was recently confirmed for the I 6 * and I 4 lines, 11 which unambiguously proved the C 7 character of the involved hole. In the Faraday geometry (Bkc, ckk), two circularly polarized optical transitions can be observed for D Fig.…”

“…2-10 Only until most recently, the former ordering of the VB states became favored, based on first-principle band structure calculations 8 and detailed magneto-optical studies [10][11][12] of the donor bound excitons involving an A-VB hole (DX A ). These studies have also provided consistent information regarding the sign and value of the Landé g factor for the C 7 -hole.…”

Valence-band-ordering of a strain-free bulk ZnO single crystal identified by four-wave-mixing spectroscopy technique

“…The excitons involved in the respective transitions are termed A-, B-, and C-excitons and abbreviated as X A , X B , and X C . Numerous reports have emerged over the past 50 years postulating either C 9 -symmetry [9][10][11][12][13][14][15][16][17][18] or C 7 -symmetry 1, [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] for the uppermost E 1 VB, as shown schematically on the right and left ends in Fig. 1(a), respectively.…”

Excitonic Effects and Energy Upconversion in Bulk and Nanostructured ZnO

“…Γ 7 -Γ 9 -Γ 7 vs. Γ 9 -Γ 7 -Γ 7 , was long-debated in the literature [11][12][13][14][15][16][17][18][19][20][21]. Recent experimental and theoretical studies [11,20,21] have favored the Γ 7 symmetry of the topmost A subband, which is different from other wurtzite semiconductors like CdS and GaN. This reversed symmetry between the A and B subbands was explained as being due to an effective negative spin-orbit interaction induced by the Zn (3d) band [11].…”