Electrical transport properties of p-GaTe grown by directional freezing method

Abstract

p-type GaTe single crystals have been grown using the directional freezing method with different growth rates. Temperature-dependent Hall effect and resistivity measurements were carried out in the 80-325 K temperature range and at 1.6 T magnetic field. The free carrier concentration in the exhaust region was in the range of 9 × 10 15 -8 × 10 16 cm −3 for growth rates of 3.3-0.39 µm s −1 and the hole mobility at 300 K ranged from 4.8 to 21 cm 2 V −1 s −1 . A systematic dependence of the hole carrier concentration and room temperature hole mobility on the growth rate was not observed. From temperature-dependent Hall measurements, we have found that the compensation ratio N D /N A was in the range of 0.39-0.69 regardless of the growth rate. The highest mobility of 342 cm 2 V −1 s −1 at 100 K was achieved after annealing at 200 • C for 30 min. The fitting of the temperature-dependent free carrier concentration, using the single acceptor-single donor model, was used to determine the compensation ratio. Finding N max (m * ) 3/2 = 3.15 indicates high effective mass for holes or the possibility of a few close maxima of valence band edges with different effective masses.

Measurement and modelling of the characteristic parameters for silver Schottky contacts on layered p-GaSe compound in a wide temperature range

“…Substantial values of the serial resistance at low temperatures are resulted from the bulk resistance, i.e. freeze out of the deep acceptors in the unintentionally doped GaSe [9,10,42,45,46]. As temperature lowered, free carriers are captured by the related deep acceptors located in the band gap and the GaSe exhibits semi-insulating behavior at low temperatures [45].…”

Multiple-barrier distribution behavior of Mo/p-GaTe fabricated with sputtering

“…A deep acceptor level located at 140 meV for p-GaTe has been reported in the electrical measurements [32]. Free carriers in unintentionally doped p-GaTe are supplied from deep acceptor levels [32]. Capacitance-voltage (C-V) [22] and thermally stimulated capacitance measurements (C-T V ) [45] made on p-GaTe support these results.…”

“…Thus, there may be two deep acceptor levels located above the valance band of p-GaTe. A deep acceptor level located at 140 meV for p-GaTe has been reported in the electrical measurements [32]. Free carriers in unintentionally doped p-GaTe are supplied from deep acceptor levels [32].…”

“…GaTe is a relatively known semiconductor compound [21][22][23][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]45,47] and exist successful but limited Schottky contact studies [21][22][23][37][38][39][40] made using GaTe. GaTe belongs to the III-VI group in the periodic table and has a layered nature.…”

“…This problem in p-GaTe may be overcome by capping or annealing under Te base pressure. It should be noted that annealing effect on p-GaTe is well known [32]. However, Te loss from GaTe is not expected due to self capping and fresh surfaces obtained by removing a layer of GaTe from surface after ohmic contact process followed for Schottky metalization.…”