GaN - Gallium Nitride

Impurities and defects


Undoped GaN is n-type with electron concentrations n >= 1017cm-3. The dominant donor is believed to be the nitrogen vacancy [Pankove et al.(1975)]. The binding energy of this donor is subject to large controversy. Values given range from 42(l)meV [Dingle & Ilegems (1971)] over 29(6)meV [Lagerstedt & Monemar (1974)] to 17meV [Vavilov et al.(1979)]. A deep donor level with Ed >;=10 meV is also postulated [Vavilov et al.(1979)]. No detailed information exists about the identity of these donors.


Most data have been derived from photoluminescence peaks which are caused by the recombination of free or bound electrons with bound holes.

Luminescence peak energies Epeak

Impurity Epeak Remarks Referens
Li 2.23 eV 77 K; photoluminescence Pankove et al.(1973)
Be or VGa 3.264 eV 4.2 K Ilegems & Dingle (1973)
Be-complex or BeGa 2.36 eV   Monemar, Lagerstedt & Gislanson (1980)
Mg or VGa 3.264 eV   Ilegems & Dingle (1973)
Mg-complex or MgGa 2.95 eV   Ilegems & Dingle (1973)
Monemar, Lagerstedt & Gislanson (1980)
Dy 3.15 eV 77 K Pankove et al.(1973)
Cd or VGa 3.268 eV
4.2 K
1.6 K
Monemar, Lagerstedt & Gislanson (1980);
Lagerstedt & Monemar (1974)
Cd-complex or CdGa 2.7 eV   Monemar, Lagerstedt & Gislanson (1980)
Zn or VGa 3.268 eV 4.2 K Monemar, Lagerstedt & Gislanson (1980)
Zn-complex or ZnGa
2.9 eV   Lagerstedt & Monemar (1974);
Monemar, Lagerstedt & Gislanson (1980)
ZnN (?) (B-band) 2.6 eV   Monemar, Lagerstedt & Gislanson (1980)
Zn-N (?) (C-band) 2.2 eV   Monemar, Lagerstedt & Gislanson (1980)
Zn2-N (?) (D-band) 1.8 eV   Monemar, Lagerstedt & Gislanson (1980)

Deep defect states

Undoped GaN is invariably n-type usually with a high free electron concentration (1017 ÷ 1018 cm-3) at room temperature. Although the dominant donor has not been unambiguously identified there is a consensus that it is an intrinsic defect and most probably the nitrogen vacancy [Pankove et al.(1975)]. Energies are reported ranging from 17meV [Vavilov et al.(1979)] to 42meV [Dingle & Ilegems (1971)]. The resistivity of the material can be increased dramatically by the addition of group II atoms; these elements introduce deep acceptors which compensate the native donors. The same binding energy of 225 meV is reported [Lagerstedt & Monemar (1974)] for the addition of Zn, Cd, Mg, and Be, however it seems unlikely that these four dissimilar species would be identical and consequently it has been proposed that the acceptor is actually VGa [Monemar, Lagerstedt & Gislanson (1980)]. The vacancy concentration is believed to be increased by the presence of the group II element.

Binding energies of acceptors

Impurity Binding energies, Eb Remarks Referens
VGa 225 meV 4.2 K; photoluminescence Monemar, Gislanson & Lagerstedt (1980)
Hg 410 meV 78 K;
infrared quenching
of luminescence
Ejder (1971)
Li 750 meV    
ZnGa (A-band) 480 meV 4.2 K  
370(40) meV 4.2 K; photoluminescence Monemar, Gislanson & Lagerstedt (1980)
ZnN (B-band) 650(80) eV    
Zn-N (C-band) 1020(50) meV    
Zn2-N (D-band) 1420(80) meV